Increased T-cell tumor infiltration and eradication of metastases by mutant light

ABSTRACT

Mutant LIGHT expressed in a tumor environment elicited high levels of chemokines and adhesion molecules, accompanied by massive infiltration of naïve T lymphocytes. Methods and compositions to elicit immune responses against tumors including tumor volume reduction and eradication of metastasis using mutant LIGHT are disclosed.

This application is a continuation-in-part of U.S. Ser. No. 10/865,623,filed Jun. 10, 2004, which claims priority from U.S. Ser. No. 60/477,733filed Jun. 11, 2003 and U.S. Ser. No. 60/478,126 filed Jun. 12, 2003.

The government has rights in the invention due to partial support fromNIH R01 HD 37104, R01-062026, and R01-DK58897.

BACKGROUND OF THE DISCLOSURE

The paucity of activated T cells infiltrating established tumors inimmunocompetent hosts helps to explain the inability of hosts to disposeof tumors. Experiments in animal models as well as clinical studiesindicate that the immune system can recognize and kill individual tumorcells, but a host cannot generally eradicate established solid tumors.There may be several explanations for the failure of the host to respondeffectively to established tumors: 1) lack of early T cell priming dueto poor direct or indirect presentation in lymphoid tissues because ofan inadequate number of tumor cells (especially those of non-hemopoieticorigin) migrating to the lymphoid tissue; 2) inadequate numbers ofimmune cells migrating to tumor sites due to biological barriers aroundtumor tissues; 3) exhausted or short-lived activated antigen-specific Tcells that fail to combat tumor growth due to limited repertoires; 4)unresponsiveness or ignorance of T cells to tumors; 5) an inhibitorymicroenvironment or lack of stimulation inside tumors to activate theimmune system.

Clinically, increase of infiltration of T cells to the tumor site isclosely associated with better prognosis. Previous studies have shownthat preventive vaccinations were effective in inducing the rejection ofinoculated tumor cells. After tumor growth has been established,however, the therapeutic vaccinations usually fail to reject tumors.Surgical debulk of tumor does not boost the immune response to tumors.Furthermore, it was reported that even the expression of a strongantigen on tumor cells was insufficient in promoting the rejection of anestablished tumor, despite the presence of excessive numbers ofantigen-specific T cells in the lymphoid tissues. Lack of T cellspriming and/or infiltrating an established tumor is one of the majorobstacles for either natural or therapeutic approaches against antigeniccancers. In addition, insufficient expression of costimulatory moleculesinside tumor tissues may fail to activate infiltrating T cells andresult in the anergy of tumor-reactive T cells.

The lack of early T cell priming is possibly attributed to only a fewtumor cells that migrated from solid tissue to lymphoid tissues fordirect presentation. Genetic analysis using bone marrow chimeras hasrevealed two modes of antigen presentation for priming MHC-I-restrictedCD8⁺ T cells. Direct-priming is mediated by the engagement of T cellswith the cells that synthesize the protein with antigenic epitopes,whereas cross-priming is mediated by the host antigen-presenting cellsthat take up antigens synthesized by other cells. The mechanisms forpriming tumor-specific T cells has been vigorously debated and so farremains inconclusive. Understanding how and where tumor antigens arepresented to T cells would help find a therapeutic action againsttumors.

LIGHT (homologous to lymphotoxin, exhibits inducible expression, andcompetes with HSV glycoprotein D for herpes virus entry mediator, areceptor expressed by T lymphocytes) is a recently identified type IItransmembrane glycoprotein of the TNF ligand superfamily. LIGHT(TNFSF14) is a tumor-necrosis factor (TNF) family member that interactswith Lymphotoxin β receptor (LTβR) and herpes virus entry mediator(HVEM) mainly expressed on stromal cells and T cells, respectively. LTβRsignaling is required for the formation of organized lymphoidstructures, which can be attributed, at least in part, to its ability toinduce the expression of chemokines and adhesion molecules that attractnaïve T cells and dendritic cells (DC) in lymphoid organs. Stimulationof LTβR on stromal cells by LIGHT in vivo leads to the expression ofCCL21, which attracts naïve T cells in the T cell area of the spleen inthe absence of LTαβ, another ligand for LTβR. These results demonstratethat LIGHT is able to interact with LTβR to regulate CCL21 chemokineexpression. In addition, LIGHT also exhibits a potent, CD28-independentco-stimulatory activity for T cell priming and expansion leading toenhanced T cell immunity against tumors and/or increased autoimmunity.Signaling via LTβR is required for the formation of organized lymphoidtissues. Lymphotoxin β receptor (LTβR) plays an important role in theformation of lymphoid structures. LTβR is activated by two members ofthe TNF family, membrane lymphotoxin αβ and LIGHT (FIG. 1). LTβR playspivotal roles in the formation of LNs and the distinct organization ofT, B zones in secondary lymphoid organs. Signaling via LTβR regulatesthe expression of chemokines and adhesion molecules within secondarylymphoid organs. Chemokines and adhesion molecules control the migrationand positioning of DCs and lymphocytes in the spleen. Over-expression ofsoluble LT or TNF in non-lymphoid tissues was sufficient to promotefunctional lymphoid neogenesis.

LIGHT plays a unique role in T cell activation and the formation oflymphoid tissue. LIGHT is a ligand for LTβR and herpes virus entrymediator (HVEM). LIGHT is predominantly expressed on lymphoid tissues.Interactions between LIGHT and LTβR restore lymphoid structures in thespleen of LTα^(−/−) mice. In addition, upregulation of LIGHT causes Tcell activation and migration into non-lymphoid tissues and formslymphoid-like structures. Conversely, LIGHT^(−/−) mice showed impaired Tcell activation and delayed cardiac rejection. Therefore, LIGHT is apotent costimulatory molecule that also promotes the formation oflymphoid tissues to enhance local immune responses. Lack of efficientpriming of naïve T cells in draining lymphoid tissues and the inabilityto expand tumor-specific T cells within tumors prevent the eradicationof cancer.

Micrometastases (small aggregates of cancer cells visiblemicroscopically) can become established at a very early stage in thedevelopment of heterogeneous primary tumors and seed distal tissue sitesprior to their clinical detection. For example, the detectablemetastasis in breast cancer can be observed when the primary tumor sizeis very small. Therefore, at the time of diagnosis many cancer patientsalready have microscopic metastasis, an observation that has led to thedevelopment of post-surgical adjuvant therapy for patients with solidtumors. Despite these advances, success has been limited, and optimaltreatment of metastatic disease continues to pose a significantchallenge in cancer therapy.

A variety of human and murine cancers have been proven to be antigenicand able to be recognized by T cells. Tumor-reactive T cells couldtheoretically seek out and destroy tumor antigen-positive cancer cellsand spare the surrounding healthy tissues. However, the naturallyexisting T cell responses against malignancies in human are often notsufficient to cause regression of the tumors, primary or metastases. Ithas been recently reported that sporadic spontaneous but immunogenictumors avoid destruction by inducing T cell tolerance but thatactivation of tumor antigen-specific T cells may completely prevent thedevelopment of spontaneous tumors. Thus, breaking tolerance andgenerating such T cells capable of rejecting tumors around the time oftreatment of the primary tumor could represent a potential approach toclearing metastatic tumor cells. As antigen-lost variants can escapeunder immunological pressure, immunotherapy should be applicableindependent of knowledge of specific tumor antigens.

From an immunological perspective, present clinical strategies hinderthe immune defense against malignancies and further diminish theeffectiveness of immunotherapy. Although removal of a tumor may reversetumor-induced immune suppression, surgical excision of the primary tumorbefore immunotherapy also removes the major source of antigen, which maylead to a reduction of the activation of CTLs since the efficiency ofpriming is correlated with the tumor antigen load. In addition,currently utilized adjuvant treatment with chemotherapy and radiationtherapy that is meant to kill residual tumor cells may in fact impairanti-tumor immune responses by destroying or inhibiting T cells.

A challenge in developing an effective immunotherapy is to devise anapproach to increase the number or enhance the function of circulatingtumor-specific T cells that may detect and destroy microscopicmetastatic cells before they become clinically meaningful.

In the present disclosure, inducing immune responses in tumor tissuesvia mutant LIGHT prior to surgery generated sufficient primedantigen-specific effector T cells to exit the tumor and eradicatemetastasis. Delivery of mutant LIGHT, using a recombinant adenovirusinto to the primary tumor of 4T1 mammary carcinoma bearing mice alsomediated prevention and eradication of spontaneous metastasis.

SUMMARY

“Mutant LIGHT” refers to a LIGHT protein or a LIGHT-derived peptide thatis resistant to proteolytic cleavage, stably expressed in the surface oftumor cells, and exhibits increased activation of tumor specificT-cells, compared to normal or native LIGHT protein.

Mutant LIGHT creates a lymphoid-like microenvironment that expresseschemokines, adhesion molecules and co-stimulatory molecules for primingT-cells to kill tumor cells.

Mutant LIGHT resists protease digestion and is expressed on tumor cells.Non-mutant LIGHT is not expressed on the surface of tumors and does notinduce effective anti-tumor activity.

Mutant LIGHT-expressing tumors as a therapeutic vaccine attracts morenaïve T cells and then activates them so that more anti-tumor specific Tcells are generated to combat local and distal tumors.

Mutant LIGHT and tumor (or tumor antigens) prime T cells and lead tolong-term protection as a preventive vaccine.

A novel method to treat tumors (solid tumors in particular) is to createlymphoid-like microenvironments that express chemokines, adhesionmolecules, and costimulatory molecules required for priming naïve Tcells and expanding activated T cells by the use of mutant LIGHTmolecules. Broader T cells are generated against tumors. Adenoviralvectors that include mutant LIGHT encoding sequences, are effectiveagainst tumors and metastasis. Tumor volume was reduced in vivo whenvectors delivered mutant LIGHT to tumors as compared to tumors injectedwith control vectors.

Also described is method of reducing cancer metastasis, including thesteps of:

-   -   (a) introducing a nucleic acid molecule encoding mutant LIGHT or        a fragment thereof into a tumor site, wherein the mutant LIGHT        does not have a proteolytic site;    -   (b) expressing the nucleic acid molecule in the tumor; and    -   (c) reducing cancer metastasis by stimulating activation of        tumor-specific T-cells against the tumor.

In various embodiments, the mutant LIGHT has an amino acid change in aproteolytic site including an amino acid sequence EQLI (SEQ ID NO: 17)from positions 81-84 of native LIGHT protein; the mutant LIGHT does nothave the proteolytic site, an amino acid sequence EQLI (SEQ ID NO: 17)from positions 81-84 of native LIGHT protein; the mutant LIGHT has anamino acid change in a proteolytic site comprising an amino acidsequence EKLI (SEQ ID NO: 4) from positions 79-82 of native LIGHTprotein; the mutant LIGHT does not have the proteolytic site comprisingan amino acid sequence EKLI (SEQ ID NO: 4) from positions 79-82 ofnative LIGHT protein.

The nucleic acid molecule disclosed encodes a recombinant mutant LIGHTincluding an extracellular domain: (SEQ ID NO: 1)

QLHWRLGEMVTRLPDGPAGSWEQLIQERRSHEVNPAAHLTGANSSLTGSGGPLLWETQLGLAFLRGLSYHDGALVVTKAGYYYIYSKVQLGGVGCPLGLASTITHGLYKRTPRYPEELELLVSQQSPCGRATSSSRVWWDSSFLGGVVHLEAGEKVVVRVLDERLVRLRDGTRSYFGAFMV.

The nucleic acid molecule is introduced into a tumor by a nucleic aciddelivery system, e.g., a viral vector. The viral vector is suitablyselected from adenovirus, adeno-associated virus, lentivirus, andretrovirus.

The nucleic acid molecule is introduced directly into a tumor or isintroduced adjacent to a tumor.

Cancer metastasis is reduced by stimulation of cytotoxic T-lymphocytes,and/or by stimulation of production of chemokines, adhesion molecules,and costimulatory molecules for priming naïve T-cells.

A method of reducing cancer metastasis includes the steps of:

-   -   (a) obtaining cells from a tumor from an individual diagnosed        with cancer;    -   (b) introducing a nucleic acid molecule encoding mutant LIGHT or        a fragment thereof into the cells, wherein the mutant LIGHT does        not have a proteolytic site;    -   (c) culturing the cells expressing the nucleic acid molecule in        a suitable growth medium;    -   (d) delivering the cells containing mutant LIGHT into the        individual; and    -   (e) reducing cancer metastasis by stimulating activation of        T-cells against tumor cells.

Cells are delivered to a pre-existing tumor site, and/or to a sitedistal to a pre-existing tumor site. The delivered cells are in theconcentration range of about 10,000 to about 1,000,000 cells per dose.Cells may be delivered after the removal of a tumor, and/or prior to theremoval of a tumor.

The cancer types treated include breast cancer, lung cancer, prostratecancer, colon cancer, and skin cancer.

A method of inducing tumor-specific T-cell generation to controlmetastasis includes the steps of:

-   -   (a) introducing a nucleic acid molecule encoding mutant LIGHT or        a fragment thereof into an individual at a tumor site, wherein        the mutant LIGHT does not have a proteolytic site; and    -   (b) controlling metastasis by inducing T-cell generation,        wherein the T-cells destroy initiation of metastasis.

T-cells are activated within a tumor site, and may circulate in blood.Circulating T-cells are preferably cancer specific. The nucleic acid isintroduced into a tumor cell in vitro and the tumor cell expressing thenucleic acid is delivered into the individual in vivo. The T-cellgeneration may be CD8+ dependent.

A therapeutic vaccine includes a tumor cell expressing a mutant LIGHTmolecule, wherein the mutant LIGHT is resistant to protease digestion.In the embodiments, the mutant LIGHT molecule does not contain aproteolytic site selected from EQLI (SEQ ID NO: 17) and EKLI (SEQ ID NO:4). The tumor cell expresses a mutant LIGHT including the extracellulardomain of native LIGHT that is resistant to protease digestion. Themutant LIGHT does not include the proteolytic site selected from EQLI(SEQ ID NO: 17) or EKLI (SEQ ID NO: 4) of native LIGHT protein. Theproteolytic site may be mutated to render it resistant to proteasedigestion.

Tumor cells number about 10,000 to about 1,000,000 cells per vaccinedose.

An isolated tumor cell is described that expresses a protease digestionresistant form of mutant LIGHT. The mutant LIGHT may be expressed on thesurface of the tumor cell.

A genetic construct includes a mutant LIGHT nucleotide sequence, whereinthe nucleotide sequence encodes a mutant LIGHT that is resistant toprotease digestion, and the mutant LIGHT is adequate to generatetumor-specific T-cells.

An isolated recombinant nucleic acid includes a nucleotide sequenceencoding a protease digestion resistant mutant LIGHT. An embodiment ofthe nucleotide sequence is: (SEQ ID NO: 2)ATGGAGGAGAGTGTCGTACGGCCCTCAGTGTTTGTGGTGGATGGACAGACCGACATCCCATTCACGAGGCTGGGACGAAGCCACCGGAGACAGTCGTGCAGTGTGGCCCGGGTGGGTCTGGGTCTCTTGCTGTTGCTGATGGGGGCTGGGCTGGCCGTCCAAGGCTGGTTCCTCCTGCAGCTGCACTGGCGTCTAGGAGAGATGGTCACCCGCCTGCCTGACGGACCTGCAGGCTCCTGGGAGCAGCTGATACAAGAGCGAAGGTCTCACGAGGTCAACCCAGCAGCGCATCTCACAGGGGCCAACTCCAGCTTGACCGGCAGCGGGGGGCCGCTGTTATGGGAGACTCAGCTGGGCCTGGCCTTCCTGAGGGGCCTCAGCTACCACGATGGGGCCCTTGTGGTCACCAAAGCTGGCTACTACTACATCTACTCCAAGGTGCAGCTGGGCGGTGTGGGCTGCCCGCTGGGCCTGGCCAGCACCATCACCCACGGCCTCTACAAGCGCACACCCCGCTACCCCGAGGAGCTGGAGCTGTTGGTCAGCCAGCAGTCACCCTGCGGACGGGCCACCAGCAGCTCCCGGGTCTGGTGGGACAGCAGCTTCCTGGGTGGTGTGGTACACCTGGAGGCTGGGGAGAAGGTGGTCGTCCGTGTGCTGGATGAACGCCTGGTTCGACTGCGTGATGGTACCCGGTCTTACTTCGGGGCTTTCATGGTGTGA, wherein the sequenceencoding the protease digestion site GAGCAGCTGATA (SEQ ID NO: 24) ismutated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a current model for the interactions betweenTNF/LT/LIGHT family members. LTβR binds to both membrane LT and LIGHT,while HVEM binds to LIGHT. Soluble TNF3 and LTα3 bind to TNFRI andTNFRII.

FIG. 2 shows that both mutant LIGHT and antigen specific T cells arerequired for optimal tumor rejection. Tumor cells (5×10⁵) wereinoculated into CB6F1: Tumor transfected with mutant LIGHT on the leftside and control tumor on the right side. Fourteen days later, 2C Tcells (10×10⁵) were transferred into the mice and tumor growth wasmonitored. Tumor growth curves are shown.

FIG. 3 shows the growth kinetics of mutant LIGHT-expressing Ag104L^(d)and parental tumor in C3B6F1 and B6/RAG-1^(−/−)mice. A. Four amino acids(SEQ ID NO: 4) corresponding to a proteolytic site were deleted from theextracellular domain of LIGHT to ensure stable expression on the surfaceof tumor cells. B. Ag104L^(d) parental tumor cells, Ag104L^(d) tumorcells transfected with mutant LIGHT, as bulk or cloned, were stainedwith LTβR-human Ig, HVEM-murine Ig, followed by FITC-conjugated donkeyantibody against human IgG or goat antibody against murine IgG,respectively (solid lines). Tumor cells stained with second-stepantibody alone were shown in dotted lines. C. C3B6F1 mice wereinoculated subcutaneously with 5×10⁶ Ag104L^(d) parental tumor cells(solid diamonds) or mutant LIGHT-expressing Ag104L^(d) tumor cells (opendiamonds). Ag104L^(d) grew progressively while Ag104L^(d)-mutant LIGHTwas rejected in C3B6F1 mice. D. B6/RAG-1^(−/−)mice were challenged withsubcutaneous injection of 10⁶ Ag104L^(d) tumor cells (solid diamonds) ormutant LIGHT-expressing Ag104L^(d) tumor cells (open diamonds). Bothtumors grew progressively in the B6/RAG-1^(−/−)mice.

FIG. 4 shows that a modified extracellular domain of mutant LIGHT issufficient to co-stimulate purified T cell responses. A. Recombinantprotein containing an extracellular domain of mutant LIGHT (85-239 aminoacids) and a flag sequence to facilitate purification of recombinantprotein. B. Purified T cells were stimulated with immobilizedextracellular domain of mutant LIGHT in the presence of antibody againstCD3 (anti-CD3).

FIG. 5 shows photographic illustrations of increased infiltration ofCD8⁺ T cells in mutant LIGHT-expressing Ag104L^(d) tumor tissues. 5×10⁶Ag104L^(d), Ag104L^(d)-B7.1 or Ag104L^(d)-mutant LIGHT tumor cells wereinjected subcutaneously to C3B6F1 mice. Tumor tissues were collected10-14 days after tumor inoculation. Frozen sections of tumor tissueswere stained with HE (upper panel) or anti-Th1.2-PE (middle panel),anti-CD8-PE, as indicated (lower panel).

FIG. 6 A. illustrates increased LTβR-associated chemokines and adhesionmolecules in Ag104L^(d)-mutant LIGHT tumors. (1) 5×10⁶ Ag104L^(d), (2)Ag104L^(d)-B7.1 or (3) Ag104L^(d)-mutant LIGHT tumor cells wereinoculated subcutaneously into C3B6F1 or B6/RAG-1^(−/−) mice. Tumortissues were collected 10-14 days post tumor challenge. B. The sameamount of tumor tissue was thoroughly ground in the PBS containingprotease inhibitors. SLC in the supernatant was measured by ELISA aftercentrifugation. Ag104L^(d)-mutant LIGHT tumors collected from bothC3B6F1 mice and B6/RAG-1^(−/−) mice, as indicated, contained higherlevel of SLC than the parental tumors. C. Tumor tissues from Ag104L^(d),Ag104L^(d)-B7.1 or Ag 104L^(d)-mutant LIGHT were fixed in 10% neutralformalin, sectioned and stained with anti-murine SLC followed by secondstep antibody, color development (red) is shown by arrows; backgroundwas hemotoxilyn counter-stained (blue). D. Total RNA was isolated fromthe tumor tissue and real-time quantitative RT-PCR was performed toanalyze the expression of adhesion molecule MAdCAM-1 and chemokine SLC.E. Gene array was performed to analyze the expression of otherchemokines as indicated in the mutant LIGHT-expressing Ag104L^(d) andparental tumor using total RNA purified from the tumor tissue. Theincrease of LTβR-associated chemokines and adhesion molecules was foundin the Mutant LIGHT-expressing tumor tissues. Relative expression levelswere shown in the left panel. Fold of increase of expression by Ag104L^(d)-mutant LIGHT was shown in the right panel. Total RNA wasisolated from the tumor tissue and gene array was performed to analyzethe expression of chemokines as indicated in the mutant LIGHT-expressingAg104L^(d) and parental tumor.

FIG. 7 shows that Mutant LIGHT-mediated Ag104Ld tumor environmentrecruits naïve 2C T cells, activates them and causes tumor rejection. A.Ag104Ld and Ag104Ld-mutant LIGHT expressed the same level of antigen Ld.Ag104Ld (black solid line) or Ag104Ld-mutant LIGHT (gray solid line)tumor cells were stained with anti-Ld followed by second step stainingof FITC-conjugated goat antibody against murine IgG. Tumor cells stainedwith second-step antibody alone were shown in dotted lines. B.OT-1/RAG-1−/− mice were injected with 10 ⁶ Ag104Ld or Ag104Ld-mutantLIGHT tumor cells subcutaneously. 3×10⁶ CFSE-labeled 2C TCR transgenic Tcells were transferred to these mice 10-14 days after tumor challenge.Tumor draining lymph nodes, non-draining lymph nodes, spleen and tumortissue were collected 48, 132, 168 and 336 hours, as indicated, after 2CT cell transfer. T cells infiltrating tumors were isolated by apositive-selecting magnetic column. Cells from lymph nodes, spleen andtumor were subjected to FACS analysis after stained with anti-CD8 and 2CTCR clonotypic antibody 1B2. Proliferation of CD8 and 1B2 doublepositive 2C T cells was shown. OT-1/RAG-1−/− mice were injected with 10⁶Ag104Ld or Ag104Ld-mutant LIGHT tumor cells subcutaneously. 3×10⁶CFSE-labeled 2C TCR transgenic T cells were transferred to these mice10-14 days after tumor challenge. Tumor draining lymph nodes,non-draining lymph nodes, spleen and tumor tissue were collected 48, and336 hours, after 2C T cell transfer. T cells infiltrating tumors wereisolated by a positive-selecting magnetic column. Cells from lymphnodes, spleen and tumor were subjected to FACS analysis after stainedwith antibody 1B2 and antibodies against activation markers CD62L orCD44. CD62L or CD44 expression by 1B2 positive 2C T cells was shown. C.OT-1/RAG-1−/− mice were injected with 10 ⁶ Ag104Ld or Ag104Ld-LIGHTtumor cells subcutaneously. 3×10⁶ 2C TCR transgenic T cells weretransferred to these mice 10-14 days after tumor challenge. Adoptivelytransferred 2C T cells were able to suppress the growth of mutantLIGHT-expressing Ag104Ld in the OT-1/RAG-1−/− hosts but not the parentaltumors.

FIG. 8 shows that intra-tumor injection of mutant LIGHT-expressingAg104L^(d) eradicates established parental tumors. 10⁵ Ag104L^(d) tumorcells were inoculated to C3B6F1 mice followed by intra-tumor injectionof 10⁶ mutant LIGHT-expressing tumor cells or PBS as control asindicated 14 days after challenge of parental tumor. Ag104L^(d) tumorstreated with Ag104L^(d)-mutant LIGHT were rejected while the onestreated with PBS grew progressively.

FIG. 9 shows a nucleic acid sequence (SEO ID NO: 3) that encodes a LIGHTprotein. The start codon ATG is indicated in bold and the regionencoding a proteolytic site that has been deleted in mutant LIGHT isunderlined.

FIG. 10 shows that delivery of mutant LIGHT by adenovirus into tumortissues allows effective immune response and tumor rejection. C3B6F1mice were inoculated with 2×10⁵ d tumor cells, followed by anintratumoral injection of 5×10¹⁰ mutant LIGHT-expressing adenovirus(left) or LacZ-expressing adenovirus as indicated (right) 14 d afterparental tumor challenge. Tumor volume was calculated by formula(length×width×height)/2.

FIG. 11 shows inhibition of 4T1 tumor growth and reduction inspontaneous metastatic tumors. At Day 0 4T1 mice were inoculated withcontrol, mutant LIGHT or Mutant LIGHT and anti 4-1 BB. At Day 7Ad-mutant LIGHT (or D10 2A) showed some reduction, at Days 14 and 17this volume reduction was more pronounced. At Day 19 tumors are removed.At Day 34 tissues were checked for lung metastasis.

FIG. 12 shows results of a clonogenic assay of the treatment groups' ofFIG. 11. Metastases in mice treated with Ad-mutant LIGHT with andwithout 41 BB were prevented.

FIG. 13 shows that intratumoral Ad-mutant LIGHT treatment inhibits thegrowth of the primary tumors. A. 1×10⁶ tumor cells were plated in 100 mmcell culture dish for 24 hours then infected with Ad-mutant LIGHT at4×10⁸ pfu/ml for 24 hours. Cells were harvested and checked for mutantLIGHT expression by FACS staining with LTβR-Ig at 0.02 mg/mL followed by2^(nd) step antibody PE-coupled donkey anti-human IgG (white), or with2^(nd) step antibody alone as control (grey). B. Antitumor effects ofAd-mutant LIGHT on Ag104L^(d) tumors. 106 Ag104L^(d) tumor cells wereinjected subcutaneously to the C3B6F1 mice. 5×10⁹ pfu Ad-mutant LIGHT(black diamond) or control virus expressing LacZ (Ad-control) (whitediamond) were injected intra-tumorally 14 days after tumor challenge.Tumor growth was recorded. Tumor volume was calculated aslength×width×height/2. One representative of three experiments wasshown. Arrow indicates the time of injection C. Antitumor effects ofAd-mutant LIGHT on B16-SIY tumors. B6 WT mice were injectedsubcutaneously with 1×10⁶ cells near the base of the tail. 10 dayslater, 2×10⁹ PFU of either Ad-mutant LIGHT (black diamond) or Ad-Control(white diamond) was injected intratumorally. The treatment was repeated4 days later followed by continued monitoring for tumor growth. Onerepresentative of two experiments was shown. Arrows indicate the time ofinjection. D. Antitumor effects of Ad-mutant LIGHT on MC38 tumors. B6 WTmice were injected subcutaneously with 1×10⁵ cells near the base of thetail. 10 days later, 2×10⁹ PFU of either Ad-mutant LIGHT (black diamond)or Ad-Control (white diamond) was injected intratumorally. The treatmentwas repeated twice with 3 days apart followed by continued monitoringfor tumor growth. Arrows indicate the time of injection.

FIG. 14 demonstrates that Ad-mutant LIGHT treatment controls spontaneousmetastasis. A. Tumor growth curve by the effects of Ad-mutant LIGHT onthe primary 4T1 mammary carcinoma. 1×10⁵ cells of 4T1 cells wereinjected subcutaneously into the flank of Balb/C mice on day 0.7 dayslater, 5×10⁹ PFU of Ad-mutant LIGHT (black square) or Ad-control (whitesquare) was intratumorally administered and tumor growth was continuallymonitored. Data is given as tumor volume (mean±SD). The data isrepresentative of two independent experiments with similar results. B-C.Local expression of mutant LIGHT on 4T1 tumor cells prevents thedevelopment of spontaneous metastasis. In vitro cultured 4T 1 mammarycarcinoma (1×10⁶ cells) were infected with Ad-mutant LIGHT or Ad-Control(4×10⁸ PFU/ml) for 24 hours then injected with 1×10⁵ cellssubcutaneously in the flank of Balb/c mice. Tumor growth was monitored(B) until mice were sacrificed on day 35 post tumor inoculation for lungcolonogenic assay (C). Data is a representative of two experiments. D.Intratumoral injection of Ad-mutant LIGHT into 4T1 cells prevents thespread of metastasis. 1×10⁵ cells of 4T1 mammary carcinoma cells wereinjected subcutaneously into the flank of Balb/c mice. On Day 7 posttumor inoculation, Ad-mutant LIGHT or Ad-Control (5×10⁹ PFU) wasinjected intratumorally. Primary tumor was surgically removed on Day 18and mice were sacrificed on Day 35 post tumor inoculation for lungcolonogenic assay. Data is representative of two independentexperiments.

FIG. 15 shows that Ad-mutant LIGHT treatment eradicates establishedmetastasis. A. 4T1 mammary carcinoma cells injected subcutaneously inthe flank of Balb/c mice were treated with Ad-mutant LIGHT or Ad-control(2×10⁹ PFU) intratumorally on days 14 and 17 post tumor inoculation.Primary tumors (˜150 mm³) were surgically resected on Day 28 and micewere sacrificed for colonogenic lung assay on day 35. Data is arepresentative of three experiments. B. Vaccination with irradiatedautologous tumor cells eradicates established metastasis. 6×10⁴ cells of4T1 tumor cells were inoculated subcutaneously in the flank of Balb/cmice on day 0. Primary tumors were surgically removed on day 18 followedby subcutaneous injection with Ad-mutant LIGHT or Ad-Control (4×10⁹ pfu)infected and irradiated 4T1 cells (1×10⁶ cells) in the mammary fat pad.On day 21, a second vaccination of freshly prepared cells were injectedin the mammary pad of mice. Mice were sacrificed on day 45 post tumorinoculation and analyzed by the lung colonogenic assay. Data isrepresentative of two independent experiments.

FIG. 16 demonstrates that antigen-specific T cells stimulated by mutantLIGHT inside the tumor traffic to the distal sites. A.10⁶ Ag 104L^(d) orAg 104L^(d)-mutant LIGHT cells expressing the same amount of L antigenwere inoculated subcutaneously to OT-1 mice. After 10-14 days, 3×10⁶CFSE-labeled 2C T cells were infused to these OT-1 mice. The expressionof CD44 and secretion of IFN-γ by 2C T cells were evaluated 14-20 daysafter adoptive transfer in the draining lymph nodes (DLNs), non-DLNs andspleen, and in the tumor itself. B-C. Each of the OT-1 mice wasinoculated with two tumors. The primary tumor was either 10⁶ Ag104L^(d)or Ag104L^(d)-mutant LIGHT, while the secondary one was 10⁵ Ag104L^(d)tumor cells. 10-14 days post tumor challenge 3×10⁶ CFSE-labeled 2C Tcells were infused into mice. Presence and CFSE dilution of the 2C Tcells were evaluated at days 3, 5 and 10 after adoptive transfer insidethe primary and the secondary tumors (B). The percentage of 2C T cellsin the secondary tumors in the hosts bearing a mutant LIGHT-expressingAg104L^(d) or parental Ag104L^(d) was compared (C). D. T cells from thelymphoid organs of Ad-mutant LIGHT-treated mice mediate the rejection ofestablished tumors upon adoptive transfer. 10⁵ Ag104L^(d) tumor cellswere inoculated to the C3B6F1 mice. The mice were then treated with5×10¹⁰ virus particles of Ad-mutant LIGHT or Ad-control 14 days posttumor challenge. 7 days after the treatment, we collected the spleen andlymph nodes from the treated mice and purified the T cells andadoptively transferred 10⁷ of these T cells to C3B6F1 mice bearing anAg104L^(d) tumor that has been established for 7 days. The tumor growthon these mice was monitored.

FIG. 17 shows that Ad-mutant LIGHT treatment on the primary tumorinduces strong anti-tumor immune responses in the secondary tumor. Eachof the C3B6F1 mice was inoculated with 10⁵ Ag104L^(d) and 10⁵ Ag104L^(d)tumor cells 6 days after primary tumor challenge. The intra-tumorAd-mutant LIGHT treatment with 5×10¹⁰ adenovirus particles on theprimary tumor inoculation was given 5 days after the secondary tumorinoculation. The growth of both of the primary and secondary tumors wasmonitored (A). The percentage of CD8⁺ T cells among Ly5.2⁺ cells, andIFN-γ-producing CD8+ T cells among CD8+ T cells in the DLN, spleen,primary and secondary tumors were examined (B) and the statistics wascalculated (C). The spleen and tumor tissues were harvested 7 days afterAd-mutant LIGHT or Ad-control treatment, ground the tissues andcollected the supernatant for cytokine measurement (D).

FIG. 18 shows LIGHT and mutant LIGHT expression in “293 cells”. 293 cellline, which is commonly used for transient expression of the gene, wasinfected with murine ad-wt LIGHT or ad-mutant LIGHT, ad-mutant LIGHTwith further codon modification that enhances RNA expression. After 48hours, 5×10e5 of the cell line was stained for 1 ung of murine LTbR-Ig(followed by anti-Ig FITC for its surface expression of LIGHT. Upperpanel shows the histogram of flowcytometry. Cells were also examinedvisually by fluorescent microscopy. Representative results are shown inlower panel. Wt LIGHT is poorly expressed on 293 cell line while mutantLIGHT expression was enhanced. Codon modification of mutant LIGHTexpressed its highest level (see example 15). Therefore, the dataconfirms that gene modification and mutation leads to higher expressionof LIGHT on cell surface for its biological activity.

FIG. 19 shows expression of human mutant LIGHT in AD293cells/adv-cmv-null (+) and AD293 cells/adv-cmv-mutant hLIGHT#7 (*).AD293cell line was infected with control adenovirus with CMV promoter alone(+) or adenovirus-LIGHT (*). The ratio of cell v. viral units is 1:100.After 48 hours, the cell line was stained with human LTbR-Ig, or mouseLTbR-Ig, and mouse HVEM-Ig. Mutant human LIGHT can bind to human LTbR,mouse LTbR, and mouse HVEM, suggesting the mutant LIGHT does not loseits capacity to bind its two known receptors.

FIG. 20 illustrates human mutant LIGHT expression on mouse and humantumor cell lines. hMe: human melanoma. Three human lines are included.1:40 means one tumor: 40 adenovirus infected unit. 4T1 is a mouse lineto express mutant LIGHT, used here as a positive control. The stainingwas done 24 hours after infection. Red line is ad-LIGHT infected cellswhile blue is parent tumor (with control ad-Laz).

FIG. 21 shows increased LTβR-regulated chemokines and adhesion moleculesin Ag104L^(d)-LIGHT tumors. C3B6F1 and B6-Rag1 ^(. . . / . . .) micewere inoculated subcutaneously with Ag104L^(d), Ag104L^(d)-LIGHT andAg104L^(d)-B7-1 tumor cells (C3B6F1 mice, 5×10⁶ cells, B6-Rag1^(−−−/−−−)mice, 1×10⁶ cells), and tumor tissues were collected 10-14 d afterchallenge. (a) Expression of CCL 21 measured by quantitative RT-PCR ontotal RNA derived from three independent LIGHT-expressing Ag104L^(d)tumors and three parental tumors (b) CCL 21 in homogenates fromAg104L^(d)-LIGHT tumors or parental tumors, collected from both C3B6F1mice and B6 Rag1^(−−−/−−−) mice and assayed by ELISA. (c)immunohistochemical staining of CCL21 and a hematoxylin counterstain intissues from Ag104L^(d), Ag104L^(d)-LIGHT and Ag104L^(d)-B7-1 tumors.(d) Relative expression of chemokines in LIGHT-expressing Ag104L^(d) andparental tumors. Total RNA was isolated from tumor tissue and gene arrayanalysis was done to assess chemokine expression. (e) Expression ofMAdCAM-1 measured by quantitative RT-PCR on total RNA derived from threeindependent LIGHT-expressing Ag104L^(d) tumors and three parentaltumors.

DETAILED DESCRIPTION

Expression of mutant LIGHT on tumor cells promotes tumor rejection. Thetumor Ag104A and its derivatives were used as one of tumor models.Ag104A was originally derived from spontaneous osteosarcoma inC3H(H-2^(k)) mice and even very low dose of Ag104A (104) can growaggressively in C3H or B6C3F1 mice with very little infiltrates. Whenstrong antigen, L^(d), was introduced into a tumor, the tumor remainedresistant to immune recognition, suggesting a possible strong tumorbarrier. Ag 104L^(d) tumor transfected retrovirally with mutant LIGHTstably expresses mutant LIGHT on its surface.

Mutant LIGHT-Ag104L^(d) tumor was first inoculated into B6C3F1 mice for2 weeks, then 1×10⁶ 2C T cells were transferred into the establishedtumor bearing mice. Impressively, all established MutantLIGHT-AG104L^(d) tumors (10/10) were rejected one week after thetransfer of 2C T cells while no Ag104L^(d) tumors (0/10) were rejected.Even though B7-1 is a strong costimulatory molecule for inducing T cellactivation and expansion, in contrast to mutant LIGHT, expression ofB7-1 on Ag 104L^(d) was not sufficient for the rejection of a tumor.These data suggest that mutant LIGHT is more potent than B7-1 to breaktumor tolerance. Considering the dual effect of mutant LIGHT, localexpression of mutant LIGHT at the tumor site may attract dendritic cellsand T cells across the tumor “barrier” by regulating the expression oflymphoid tissue chemokines and adhesion molecules. Furthermore, localexpression of mutant LIGHT becomes a strong costimulatory molecule thatenhances direct presentation of tumor antigens to antigen-specific Tcells and prevent the anergy of infiltrated T cells within the tumormicroenvironment. H-2b background tumors, MC57 tumors (fibrosarcoma),MC57-L^(d) and MC57-SIY with or without mutant LIGHT expression havebeen generated and are used in B6 mouse models, including LTβR, mutantLIGHT, and HVEM KO mice to further characterize the role of mutant LIGHTand its receptors in tumor immunity. Mutant LIGHT appears to havemultiple functions in mediating tumor immunity. Mutant LIGHT also mayenhance tumor apoptosis in vivo. Interestingly, intratumoral injectionof cDNA encoding mutant LIGHT induced an antigen-specific cytolyticT-cell response and therapeutic immunity against the established murinetumor P815.

Successful eradication of metastasis by currently available cancertreatments remains rare. Generating immune responses in primary tumortissues prior to surgical resection produces tumor-specific effector Tcells sufficient to eradicate distant metastases. Adenovirus expressingTNF superfamily 14 (Ad-TNFSF14, mutant LIGHT) was inoculated intoprimary 4T1 mammary carcinoma in mice subsequent to its systemicdissemination. Metastases were eradicated in a CD8-dependent fashion.Local treatment with Ad-TNFSF14 initiated priming of tumor-specific CD8⁺T cells directly in the primary tumor, with subsequent exit of cytotoxicT lymphocytes (CTL) that homed to distal tumors. Targeting primary tumorwith Ad-TNFSF14 prior to surgical excision elicits immune-mediatederadication of spontaneous metastasis.

Metastasis is often a fatal step in the progression of solidmalignancies. Disseminated metastatic tumor cells can remain dormant andclinically undetectable for months or even years following surgicalresection of the primary tumor, leading to subsequent clinical diseaserecurrence. Immunotherapeutic strategies are suitable to eliminate thismicrometastatic disease. Local delivery of mutant LIGHT into the primarytumor prevented the formation of metastasis and rejected the establishedmetastasis in peripheral tissues. Local delivery of mutant LIGHT insidetumor using adenoviral gene transfer generated sufficient number ofeffector/memory T cells from the tumor tissues that move to a distalsite, leading to an overall increase in the intensity of the immuneresponse, greater inflammatory cytokine production, and the eradicationof spontaneous metastasis. Immunotherapy using primary tumor tissuesaimed to provoke and sustain a tumor specific immune response in thepresence of endogenous tumor antigens generates the necessary CTL toclear already disseminated tumor cells.

In an aspect, adenoviral vectors form a suitable delivery system forgene therapy against tumors. For example, adenoviral vectors have afavorable safety profile; higher transduction efficiency; expression innon-dividing cells; and direct stimulation of innate immunity thatcontributes to stronger adaptive immunity. Although the adenoviralbackbone may stimulate an immune response due to its strongantigenicity, this does not appear to impede repeated injections by theintratumoral route. As disclosed herein, local administrationdemonstrate that the adenovirus delivers LIGHT into tumor cells, leadingto a strong antigen specific immune response sufficient to rejectmetastastic cells. Other viral gene delivery systems such as lentivirus,vaccinia virus, adeno-associated virus (AAV), moloney murine leukemiavirus (MoMuLV); VSV-G type retroviruses, papovaviruses such as JC, SV40,polyoma, Epstein-Barr Virus (EBV); papilloma viruses, and bovinepapilloma virus type I, and other human and animal viruses are alsosuitable.

Clearance of distal metastases are attributable to the effects of mutantLIGHT in the primary tumor, rather than a general systemic immunestimulation by the adenovirus expressing mutant LIGHT. For example, 4T1tumor cells infected with Ad-mutant LIGHT in vitro resulted in nometastasis. In this model, any remaining viral excess was washed outprior to inoculation of mutant LIGHT infected 4T1 tumor cells, thusrendering systemic stimulation by Ad-mutant LIGHT impossible (FIG. 14).4T1 tumor cells infected with Ad-mutant LIGHT as therapeutic vaccine ledto the eradication of metastasis (FIG. 15). Highly progressive tumorcells stably transfected with mutant LIGHT mediated rejection of distaltumors completely (FIG. 17). Inoculation of Ad-mutant LIGHT outside ofthe primary tumor failed to prevent lung metastasis. Targeting theprimary tumor with Ad-mutant LIGHT effectively breaks tolerance of Tcells, and promotes antigen specific CTLs to exit the primary tumor toclear metastasis or distal tumors.

4T1 mouse mammary carcinoma is a poorly immunogenic, BALB/c-derivedtransplantable tumor model that shares many characteristics with humancancers including breast cancers, and is an established model formetastatic cancers. When 10⁵ tumor cells are inoculated subcutaneously,the tumor begins to metastases to draining lymph nodes (LN), lung,liver, and other organs only 11 days post inoculation. Mice succumb tolung metastases within 5-7 weeks. Local treatment of 4T1 with Ad-mutantLIGHT on day 14, eradicated established metastatic cells in theperipheral tissues. With surgical excision of the primary tumor a weeksubsequent to dissemination of cancer cells, tumor vaccination withAd-mutant LIGHT eliminates metastases. Ad-mutant LIGHT either alone orin combination with other treatments may augment the immune response toelicit complete eradication of the more established metastases in theperiphery.

It had not been clearly demonstrated whether tumor specific CTLs thatinfiltrate the tumor site can survive to vacate the tumor and enter thedraining lymphoid organs for systemic circulation. A unique tumor model,the 2C-Ag104L^(d) system was used to trace antigen-specific T cellsinside the primary tumor, the draining LN, and secondary tumor sites.The uniqueness of the model system is that the antigen L^(d) expressedby the tumor cells can only be seen by 2C T cells directly since theL^(d) processed and presented by the antigen presenting cells (APC) froma H-2b host can not be recognized by 2C T cells. Ag104L^(d) tumor cellsinside draining LN that directly prime 2C T cells in the lymphoidtissues were not identified. Therefore, few naïve 2C T cells areactivated in the draining lymph nodes in this setting. Rather, 2C Tcells must move into the tumor site for direct encounter with theL^(d)-expressing tumor cells for initial activation, andantigen-experienced T cells present in the lymphoid organs come from thetumor microenvironment in this model system. In the presence of LIGHTinside the tumor, CTLs are efficiently primed and subsequently circulateto infiltrate LIGHT-negative distal tumors. Without the benefits ofLIGHT expression in the primary tumor, few activated T cells weredetected in draining LNs or at a secondary tumor site. It is likely thatthese effector/memory T cells generated in the local tumor site in thepresence of LIGHT are able to exit the tumor and patrol the peripheryand identify metastatic tumor cells. Chemokine receptor (CCR7) has beenrecently shown to be a key molecule for T cells to exit the peripheraltissues, including the inflammatory site, and traffic to the drainingLN. The 2C T cells exiting LIGHT-expressing tumors may be controlled byCCR7.

The model system disclosed herein allows to distinguish the tumorantigen-specific T cells activated in the lymphoid tissues before goingto the tumor versus those activated directly within the tumormicroenvironment and also examines the trafficking of the tumorantigen-specific CD8⁺ T cells in the primary tumor after localimmunotherapy.

“Mutant LIGHT” also designated as “LIGHT^(m)” relates to a LIGHT proteinor LIGHT protein derived peptides or fragments that are resistant toprotease digestion or otherwise are capable of being stably expressed onthe surface of cells including tumor cells, so that increasedtumor-specific T-cells are generated, as compared to a native LIGHTprotein. There are several ways to generate mutant LIGHT. For example,the protease site (e.g., EQLI (SEQ ID NO: 17) or EKLI (SEQ ID NO: 4))can be mutated either to remove the protease site in toto or to renderthe site resistant to protease digestion by changing (e.g., insertion,deletion, substitution) one or more amino acids at the protease site.Mutant LIGHT also includes fragments/derivatives of LIGHT protein thatare resistant to protease digestion thereby exhibiting the ability to bepresent on the cell surface for an extended period of time compared tonative LIGHT protein.

For example, an extracellular domain of LIGHT molecule can berecombinantly expressed such that either the recombinant form does nothave the proteolytic site all together or has one or more amino acidchanges that renders the recombinant form protease digestion resistant(mutant LIGHT). In addition, the extracellular domain or a functionalequivalent derivative of the extracellular domain of LIGHT can be linkedto a tether or linker or spacer sequence to anchor the extracellulardomain in the membrane of tumor cells.

“Ad-mutant LIGHT” refers to recombinant adenoviral vector system thatcontains mutant LIGHT encoding nucleic acids and is suitable fordelivering the nucleic acid sequences to a tumor site or capable ofinfecting tumor cells.

“Metastasis or metastases” refers to the process by which cancer spreadsfrom the location at which the cancer initiated as a tumor to one ormore distant locations in the body by migration of one or more cancerouscells. These terms also include micro-metastasis wherein the formationof tumors at distal locations correspond to small aggregates of cancercells that are visible microscopically. These terms also refer to thesecondary cancerous growth resulting from the spread of the primarytumor from the original location.

“Reducing or controlling metastasis” refers to a reduction in the numberof metastatic tumor sites as compared to a control.

“Adoptive transfer” refers to the transfer of T cells into recipients.

“Tumor” refers to an abnormal mass of tissue. Tumors can be benign ormalignant. Malignant tumors are cancerous.

“Cancer or cancerous” refers to an abnormal growth of cells that tend toproliferate in an uncontrolled way and, in some cases, metastasize(spread).

“Tumor site” means a location in vivo or ex vivo that contains or issuspected of containing tumor cells. Tumor site includes solid tumorsand also the locations that are adjacent or immediately near a tumorgrowth.

As used herein, the term “administration” refers to systemic and/orlocal administration. The term “systemic administration” refers tonon-localized administration such that an administered substance mayaffect several organs or tissues throughout the body or such that anadministered substance may traverse several organs or tissues throughoutthe body in reaching a target site. For example, administration into asubject's circulation may result in expression of a therapeutic productfrom an administered vector in more than one tissue or organ, or mayresult in expression of a therapeutic product from an administeredvector at a specific site, e.g., due to natural tropism or operablelinkage of tissue-specific promoter elements. One of skill in the artwould understand that various forms of administration are encompassed bysystemic administration, including those forms of administrationencompassed by parenteral administration such as intravenous,intramuscular, intraperitoneal, and subcutaneous administration. In someembodiments, systemic administration can be used to elicit a systemiceffect associated with treatment of a local or systemic disease orcondition. A systemic effect may be desirable for a local disease orcondition, for example, to prevent spread of said disease or condition.The term “local administration” refers to administration at or near aspecific site. One of skill in the art would understand that variousforms of administration are encompassed by local administration, such asdirect injection into or near a specific site. In some embodiments,local administration is associated with treatment of a disease orcondition where a local effect is desired (e.g. administration to thelung for the treatment of lung cancer). A local effect may be desired inassociation with either local or systemic diseases or conditions. Alocal effect may be desired in association with a systemic disease orcondition to treat a local aspect of a systemic disease or condition.

Specific viral vectors for use in gene transfer systems are now wellestablished and include adenoviral vectors, adeno-associated viralvectors, lentiviral vectors, baculoviral vectors, Epstein Barr viralvectors, papovaviral vectors, vaccinia viral vectors, and herpes simplexviral vectors. See for example: Madzak et al. (1992): papovavirus SV40;Moss et al. (1992): vaccinia virus; Margulskee (1992): herpes simplexvirus (HSV) and Epstein-Barr virus (EBV); Miller, (1992): retrovirus;Brandyopadhyay et al., (1984): retrovirus; Miller et al. (1992):retrovirus; Anderson, (1992): retrovirus; herpes viruses (for example,herpes simplex virus based vectors); and parvoviruses (for example,“defective” or non-autonomous parvovirus based vectors); Hofmann, et al.(1995): baculovirus; Boyce, et al. (1996): baculovirus; all of which areherein incorporated by reference. In various embodiments, recombinantviral vectors designed for use in gene therapy are used in theinvention. See, e.g., Hu and Pathak, (2000); Somia and Verma (2000); vanBeusechem et al. (2000); Glorioso et al. (2001). Additionally, viralvectors may be administered in combination with transientimmunosuppressive or immunomodulatory therapies. See, e.g., Jooss et al.(1996); Kay et al. (1994).

In other embodiments, viral serotypes, e.g., the general adenovirustypes 2 and 5 (Ad2 and Ad5, respectively) may be administered, possiblyon an alternating dosage schedule where multiple treatments will beadministered. Specific dosage regimens may be administered: over thecourse of several days, when an immune response against the viral vectoris anticipated, or both. In non-limiting examples of specificembodiments, Ad5-based viral vectors may be used on day 1, Ad2-basedviral vectors may be used on day 2, or vice versa.

In some embodiments, nucleic acids are additionally provided inreplication-defective recombinant viruses or viral vectors. These can begenerated in packaging cell lines that produce onlyreplication-defective viruses. In certain embodiments, the nucleic acidencoding a therapeutic gene product is not part of a viral vector.

Adenoviral vectors: In some embodiments, a vector for delivering anucleic acid is an adenovirus-based vector. See, e.g., Berkner et al.(1992). In some embodiments, the adenovirus-based vector is an Ad-2 orAd-5 based vector. See, e.g., Muzyczka (1992); Ali et al. (1994); andU.S. Pat. Nos. 4,797,368 and 5,399,346.

Adenoviruses can be modified to efficiently deliver a therapeutic orreporter transgene to a variety of cell types. For example, the generaladenoviruses types 2 and 5 (Ad2 and Ad5, respectively), which causerespiratory disease in humans, are currently being developed forclinical trials, including treatment of cancer or other cellproliferation diseases and disorders, and for gene therapy of DuchenneMuscular Dystrophy (DMD) and Cystic Fibrosis (CF). Both Ad2 and Ad5belong to a subclass of adenovirus that are not associated with humanmalignancies. Adenovirus vectors are capable of providing high levels oftransgene delivery to diverse cell types, regardless of the mitoticstate of the cell. High titers (10¹³ plaque forming units/ml) ofrecombinant virus can be easily generated in 293 cells (anadenovirus-transformed, complementation human embryonic kidney cellline: ATCC No. CRL1573) and cryo-stored for extended periods withoutappreciable losses. The efficacy of this system in delivering atherapeutic transgene in vivo that complements a genetic imbalance hasbeen demonstrated in animal models of various disorders. See, e.g.,Watanabe (1986); Tanzawa et al. (1980); Golasten et al. (1983);Ishibashi et al. (1993); Ishibashi et al. (1994), all of which areherein incorporated by reference. Recombinant replication defectiveadenovirus encoding a cDNA for the cystic fibrosis transmembraneregulator (CFTR) gene product has been approved for use in at least twohuman CF clinical trials. See, e.g., Wilson (1993).

Some replication-deficient adenoviruses which have been developed forclinical trials contain deletions of the entire E1a region and part ofthe E1b region. These replication-defective viruses are grown in 293cells containing a functional adenovirus E1a gene which provides atrans-acting E1a protein. E1-deleted viruses are capable of replicatingand producing infectious virus in certain cells (e.g., 293 cells), whichprovide E1a and E1b region gene products in trans. The resulting virusis capable of infecting many cell types and can express the introducedgene (providing it carries its own promoter). However, the virus cannotreplicate in a cell that does not carry the E1 region DNA unless thecell is infected at a very high multiplicity of infection. Otheradenoviral vectors developed for clinical trials may be used in theinvention. Examples include Ad vectors with recombinant fiber proteinsfor modified tropism (e.g., van Beusechem et al. (2000)), proteasepre-treated viral vectors (e.g., Kuriyama et al. (2000)), E2atemperature sensitive mutant Ad vectors (e.g., Engelhardt et al.(1994)), and “gutless” Ad vectors (e.g., Armentano et al. (1997); Chenet al. (1997); Schieder et al. (1998)).

Adenoviruses have a broad host range, can infect quiescent or terminallydifferentiated cells such as neurons, and appear to be essentiallynon-oncogenic. Adenoviruses additionally do not appear to integrate intothe host genome. Because they exist extrachromosomally, the risk ofinsertional mutagenesis is greatly reduced. See, e.g., Ali et al. 1994,supra, at 373. Recombinant adenoviruses (rAdV) produce very high titers,the viral particles are moderately stable, expression levels are high,and a wide range of cells can be infected.

Adeno-associated viruses (AAV) have also been used as vectors forsomatic gene therapy. AAV is a small, single-stranded (ss) DNA viruswith a simple genomic organization (4.7 kb) that makes it an idealsubstrate for genetic engineering. Two open reading frames encode aseries of rep and cap polypeptides. Rep polypeptides (rep78, rep68, rep62 and rep 40) are involved in replication, rescue and integration ofthe AAV genome. The cap proteins (VP1, VP2 and VP3) form the virioncapsid. Flanking the rep and cap open reading frames at the 5′ and 3′ends are 145 bp inverted terminal repeats (ITRs), the first 125 bp ofwhich are capable of forming Y- or T-shaped duplex structures. Ofimportance for the development of AAV vectors, the entire rep and capdomains can be excised and replaced with a therapeutic or reportertransgene. See, e.g., Carter (1990). It has been shown that the ITRsrepresent the minimal sequence required for replication, rescue,packaging, and integration of the AAV genome.

Administration of the viral particles comprising viral vectors describedherein can be via any of the accepted modes of administration for suchviral particles well known by a person of ordinary skill in the art. Forexample, the viral particles may be administered by systemic or localadministration, including oral, nasal, parenteral, transdermal, topical,intraocular, intrabronchial, intraperitoneal, intravenous, subcutaneous,and intramuscular administration, or by direct injection into cells,tissues, organs, or tumors. The adenoviral particles/vectors may beformulated in any art-accepted formulation well known to a person ofordinary skill in the art.

EXAMPLES

The following examples are for illustrative purposes only and are notintended to limit the scope of the disclosure.

Example 1 Mutant LIGHT Expressed Inside the Tumor Augmented HostResistance More than 500 Times

Fibrosarcoma Ag104L^(d) was highly tumorigenic and grew out 100%(enlarged tumor growth) when 10⁴ cells were injected into recipient miceC3B6F1 subcutaneously (TABLE 1). It has been reported that 2C T cellreceptor (TCR) transgenic mice, which were filled with T cells againstantigen L^(d) expressed on the tumor, failed to eradicate it even afterrejection of skin graft containing the same antigen. How to directtumor-specific T cells into the tumor and activate them at the tumorsites seems to be one critical hurdle for rejection, as well asimmunotherapy of cancer clinically. Mutant LIGHT expressed in the tumorenvironment may break the tolerance by attracting and activating T cellsinside the tumor via LTβR and HVEM, respectively, leading to tumorrejection (FIG. 2). To demonstrate this, mutant LIGHT was expressed onthis tumor cell line by retroviral transduction utilizing retroviralvector MFG. Initially, native LIGHT expression was not detected on thetumor cell surface after transduction. Because native LIGHT hasproteolytic sites in its sequence, which may prevent its stable presenceon the surface of a tumor cell line, a mutant version of LIGHT (mutantLIGHT), which reduces proteolysis of LIGHT on the membrane was used.(FIG. 3A). After retroviral transduction of mutant LIGHT/MFG toAG104L^(d), Mutant LIGHT expression was detected on the surface oftransduced tumor cells by LTβR-Ig. (FIG. 3B). These cells were definedas Ag 104L^(d)-mutant LIGHT bulk. Mutant LIGHT-expressing Ag 104L^(d)tumor cells were further cloned by limiting dilution. One of the clones,H10 was used in most of the experiments unless specified otherwise.Mutant LIGHT was able to bind both of its receptors, LTβR and HVEM.Ag104L^(d)-mutant LIGHT bulk and all the clones tested bound receptorsof mutant LIGHT, LTβR and HVEM, shown by their ability to be stained bysoluble LTβR and HVEM. The typical staining profile of Ag104L^(d)-MutantLIGHT bulk and clone H10 by LTβR-Ig and HVEM-Ig was shown (FIG. 3B). Thegrowth of parental tumor cells and mutant LIGHT-transfectants was thesame in both tissue culture and RAG-1−/− mice (FIG. 3D). Differentnumber of mutant LIGHT-expressing tumor cells, bulk or clone H10, wereinoculated subcutaneously to C3B6F1 mice. The recipients rejected thehighest dose of mutant LIGHT-expressing tumor cells injected, 5×10⁶,which was 500 times of the dose at which the parental tumors grewprogressively 100% (Table 1). The typical growth kinetics of the mutantLIGHT-expressing tumor, bulk or clone H10, and the parental one when5×10⁶ cells were inoculated was shown in FIG. 3C. Ag104L^(d)-mutantLIGHT grew in the first two weeks after inoculation followed bysubsequent regression when parental tumor continues to progress and killthe host in 3-4 weeks (FIG. 3C). The tumor rejection is likely to bemutant LIGHT-dependent since the mutant LIGHT-expressing tumors grew ifmutant LIGHT function was blocked with soluble LTβR (Table 1). The tumorrejection is dependent on lymphocytes. Mutant LIGHT-expressingAg104L^(d) grew equally progressive as the parental tumor in RAG-1^(−/−)mice, which lacked lymphocytes (FIG. 3D). CD8⁺ T cells but not CD4⁺ Tcells were essential to mediate the rejection of the mutantLIGHT-expressing Ag104L^(d) because C3B6F1 mice, which were depleted ofCD8⁺ T cells with anti-CD8 antibody, failed to reject these tumors(TABLE 1). However, CD4⁺ T cells are not required for the tumorrejection.

Example 2 Mutant LIGHT-Mediated Tumor Environment has More InfiltratingCD8+ T Cells

To investigate the possible mechanisms underlying mutant LIGHT-mediatedtumor rejection, 5×10⁶ mutant LIGHT-expressing Ag104L^(d) or the samenumber of parental tumor cells were injected subcutaneously to theC3B6F1 mice. Ten to fourteen days after tumor inoculation, before mutantLIGHT-expressing tumors were rejected, tumor tissues were collected.HE-staining of the tumor tissues showed large amount of infiltratinglymphocytes (FIG. 5) while the parental tumors showed very littleinfiltration (FIG. 5). Immunofluorescent staining confirmed that amongthe infiltrating lymphocytes, large amount of Thy1.2⁺ T cells (FIG. 5),especially CD8⁺ T cells were present inside Mutant LIGHT-expressingtumors (FIG. 5).

Example 3 Modified Extracellular Domain of LIGHT is Sufficient toCo-Stimulate T Cells

In mutant LIGHT, four amino acids corresponding to a proteolytic site inthe extracellular domain, very close to transmembrane domain of themolecule were deleted (FIG. 3A). The mutation in the mutant LIGHTmolecule affects its co-stimulatory effect. Recombinant mutant LIGHTprotein was made that only contains amino acids 85 to 239, a shortenedform of extracellular domain, with a flag peptide to facilitatepurification (recombinant mutant LIGHT) (FIG. 4A). The modifiedextracellular domain of mutant LIGHT was sufficient to co-stimulate Tcells. For this test, an in vitro co-stimulation assay with plate-boundrecombinant mutant LIGHT was used to stimulate purified mouse T cells inthe presence of an immobilized monoclonal antibody against CD3 at asub-optimal dose. Immobilized recombinant mutant LIGHT stronglystimulated a proliferation of purified mouse T cells in a dose-dependentmanner in the presence of sub-optimal amounts of antibody against CD3(FIG. 4B). The modified extracellular domain of LIGHT, which is aminoacid 85 to 239 excluding the proteolytic site deleted from the mutantLIGHT molecule, is sufficient to co-stimulate T-cell growth whenengagement of the T-cell receptor occurs.

Example 4 Tumor Expressing B7.1 Molecule Contains ComparableInfiltrating T Cells to Parental Tumor

Infiltrating CD8⁺ T cells correlated with tumor rejection by mutantLIGHT-mediated tumor environment. Because mutant LIGHT has potentco-stimulatory effect on T cells, a question was whether B7.1, anotherpotent co-stimulatory molecule is sufficient to mediate tumor rejectionassociated with large number of infiltrating T cells. 5×10⁶Ag104L^(d)-B7.1 tumor cells, which were transduced the same way asAg104L^(d)-mutant LIGHT, were inoculated to C3B6F1 mice subcutaneously.These tumors grew progressively in the recipients. HE-staining on thetumor tissues showed little lymphocyte infiltration (FIG. 5).Immunofluoresent staining with anti-Thy1.2 and anti-CD8 revealed thatAg104L^(d)-B7.1 tumor tissues contained comparable level of T cellsincluding CD8⁺ T cells infiltration with parental tumor Ag104L^(d) (FIG.5), which was substantially less comparing with mutant LIGHT-expressingAg104L^(d) (FIG. 5). This data was consistent with previous findingsthat Ag104L^(d) expressing two co-stimulatory molecules, B7.1 and CD48,failed to be rejected by 2C TCR transgenic mice. These lines of evidencesuggested that strong co-stimulation alone is not sufficient to mediatetumor rejection in these tumor models.

Example 5 Mutant LIGHT-Mediated Tumor Environment Contains High Level ofChemokine SLC and Up-Regulated Adhesion Molecule MAdCAM-1

Although mutant LIGHT binds to HVEM, the receptor expressed on T cells,via which mutant LIGHT likely mediates its co-stimulation of T cells,LTβR is another receptor interacting with mutant LIGHT. LTβR signalingis an important regulator for chemokine SLC and adhesion moleculeMAdCAM-1, which controls the homing of naïve T cells to the secondarylymphoid tissues. Mutant LIGHT in the tumor environment could interactwith LTβR on these tumor stromal cells to up-regulate SLC and MAdCAM-1in the tumor environment. Tumor tissue was collected from eitherparental Ag104L^(d) or Mutant LIGHT-expressing Ag104L^(d) 10-14 daysafter inoculation. Real time RT-PCR, showed that Mutant LIGHT-positivetumor mass expressed higher level of SLC than parental tumor (FIG. 6A).This result was independently confirmed by ELISA detecting abundance ofSLC in Ag104L^(d)-Mutant LIGHT (FIG. 6B). SLC was barely detectable inthe parental tumors (FIG. 6B). To exclude the possibility that thehigher SLC detected in the Mutant LIGHT-expressing tumor was solely dueto more vigorous ongoing immune responses with more T cells in the tumorenvironment, tumor tissues from RAG-1^(−/−) tumor bearers. Ag104Ld-Mutant LIGHT tumors growing in the lymphocyte deficient mice containedhigher level of SLC than parental tumors (FIG. 6B). Furthermore, equalgrowth of both Mutant LIGHT-positive and negative tumors in RAG-1^(−/−)mice suggested that chemokine SLC alone is not sufficient to mediatetumor rejection. These data were consistent with the immunohistochemicalstaining of tissue sections from other 5 pairs of Mutant LIGHT-positiveand negative tumor samples collected from C3B6F1 tumor bearing animals(TBA). Very strong staining of SLC was detected near stroma-rich area inthe LIGHT-expressing tumors surrounded by high density of infiltratinglymphocytes, as clearly shown by SLC and hemotoxylin double-stainedtumor tissues (FIG. 6C). However, SLC was not detected in thestroma-rich area on the tumor tissues that are negative for Mutant LIGHT(FIG. 6C). The tissues from B7.1-expressing tumors also had no SLCstaining and very few lymphocytes infiltration, similar to those ofcontrol tumors (FIG. 6C).

Adhesion molecules are critical for the migration of lymphocytes intothe peripheral tissues and LTβR signaling is important for theexpression of one of the adhesion molecules MAdCAM-1 (Kang, 2002). Theexpression level of MAdCAM-1 in the Mutant LIGHT-expressing tumor massor the parental tumor was checked by real-time RT-PCR. Increasedexpression for adhesion molecule MAdCAM-1 in the Mutant LIGHT-expressingtumor mass compared to parental ones (FIG. 6D). These experimentsstrongly suggested that LIGHT in the tumor environment interacts withLTβR derived from tumor stroma to up-regulate chemokine SLC and adhesionmolecule MAdCAM-1 to attract lymphocytes into the tumor environment.

In addition to lymphoid tissue chemokines, LTβR signaling also regulatesa set of INF-γ-induced chemokines IP-10 and Mig. A gene array to comparethe expression level of other chemokines revealed that IP-10 and Mig,which can potentially attract activated T cells, also were specificallyup-regulated in the Mutant LIGHT-mediated tumor environment comparedwith parental one while other chemokines tested were comparable betweenMutant LIGHT-positive or negative tumors. Therefore, Mutant LIGHT playsan important role in the formation of lymphoid microenvironment forrecruiting naïve and possibly activated, T cells.

Example 6 Naïve T Cells Can be Recruited into Mutant LIGHT-MediatedTumor Environment where they Proliferate and Reject Tumors

Mutant LIGHT-mediated tumor environment contains high level of chemokineSLC and adhesion molecule MAdCAM-1, which potentially allow entry ofnaïve T cells. Three questions addressed directly were: 1) whether suchenvironment is able to recruit naïve T cells; 2) whether naïve T cellscan be activated inside the tumor, in vivo, in the presence of MutantLIGHT; and 3) whether tumor bearing the antigen can be rejected by theseT cells. The antigen L^(d) expressed by Ag104, is an allogeneic MHCclass 1 molecule that presents peptides derived from the house-keepinggene α-ketoglutarate dehydrogenase, on the surface of the tumor cells.In C3B6F1 (H-2^(kXb)) or B6 (H-2^(k)) hosts, adoptively transferred 2CTCR transgenic T cells only recognize Ag104 tumor cells directlypresenting L^(d) because 2C T cell responses required L^(d) in its naïveform, which is lost when the antigen is processed and cross-presented byantigen presenting cells (APCs) from the hosts. Subcutaneously growingtumors are very inefficient to prime T cells via direct pathway in thelymphoid tissues. Ag104L^(d) inoculated subcutaneously 24 hours after3-5×10⁵ CFSE-labeled 2C T cells were adoptively transferred into theC3B6F1 hosts. Proliferation of 2C T cells was not detected or measuredby fluorescent dye CFSE dilution in the tumor draining lymph nodes,other non-draining lymph nodes or spleen up to 7 days after Ag104L^(d)tumor challenge. 2C T cells in the secondary lymphoid organs maintainedtheir naïve phenotype as indicated by low CD25, CD69 or CD44 on theirsurface during the 7-day observation. These indicated that T cellsspecific for antigens expressed on the tumor cells could not beactivated if the antigens could not be cross-presented efficiently formany reasons. Consequently, 10⁶ Ag104L^(d) tumor cells were not rejectedby C3B6 μl mice even when as many as 5×10⁶ tumor antigen specific 2C Tcells were transferred into the hosts.

To investigate what happens when adoptively transferred 2C T cells whenMutant LIGHT is present inside the tumor environment. MutantLIGHT-expressing Ag104L^(d) tumors were rejected by endogenous CD8⁺Tcells without 2C T cell transfer in C3B6F1 hosts. In order to traceantigen-specific T cells and monitor their trafficking, priming andability to reject tumors, H-Y or OT-1 TCR transgenic mice in B6(H-2^(b))/RAG-1^(−/−)background were used as recipients for tumorchallenges. These mice harbor monoclonal CD8⁺T cells that do not respondto Ag104L^(d) tumor. Thus, Ag104L^(d) or Mutant LIGHT expressingAg104L^(d) both grew aggressively in these mice similarly as in theRAG-1^(−/−)mice (FIG. 7C). However, adoptively transferred 2C T cells donot undergo vigorous homeostatic proliferation up to 14 days underconstant observation due to the presence of these CD8 ⁺H-Y or OT-1transgenic T cells in these mice (FIG. 7B). Thus, the vigorousproliferation of 2C T cells in these hosts was antigen L^(d) drivenwithin 14 days after adoptive transfer. 10⁶ Ag104L^(d) orAg104L^(d)-Mutant LIGHT, which expressed the same level of antigen L^(d)on their surface (FIG. 7A), was subcutaneously inoculated into thesemice. Then adoptively transferred 3×10⁶ CFSE labeled 2C T cells to themice 10-14 days after tumor challenge. Mice were sacrificed 48,132,168and 336 hours after T cell transfer and tumor draining lymph nodes(DLN), other non-draining lymph nodes (NDLN), spleen (SPL) and tumormass were collected. Single-cell suspension of tumor mass was obtainedby collagenase digestion. If necessary, T cells infiltrating tumors(TIL) were purified with a positively selective magnetic system fromtumor cells. 2C T cell trafficking and proliferation was evaluated.Naïve 2C T cells with high CFSE staining, high CD62L and low CD44 werepresent similarly in the secondary lymphoid organs in both Ag104L^(d) orAg104L^(d) -Mutant LIGHT bearing mice 48 hours after T cell transfer(FIG. 7B). However, a significant number of naïve 2C T cells, which areCD62L^(high) and CD44^(low), were detected inside MutantLIGHT-expressing tumors but not in the parental tumors (FIG. 7B). Thispopulation of 2C T cells proliferated inside Mutant LIGHT-expressingtumor indicated by the dilution of CFSE 132 hours after T cell transfer(FIG. 7B). At this time point, no 2C T cells, naïve or proliferated,could be detected in the parental tumors (FIG. 7B). At 168 h after 2C Tcell transfer, large amounts of proliferated 2C T cells were presentsolely in the Mutant LIGHT-expressing tumors. Up to 7 days (168 h) after2C T cell transfer, no significant CFSE-labeled 2C T cell proliferationor proliferated 2C T cells could be detected in the secondary lymphoidtissues of the mice bearing Mutant LIGHT-positive or negative tumors(FIG. 5B). Activation of 2C T cells by antigen L^(d) did not happen inthe tumor draining nodes, other lymph nodes or spleen, but only insideMutant LIGHT-positive tumor. 14 days after 2C T cell transfer, CFSE-low,fully proliferated 2C T cells were detected in the secondary lymphoidorgans of the mice bearing Mutant LIGHT-expressing tumors. The 2C Tcells present in the lymph nodes expressed high level of CD44 and CD62L.However, the 2C T cells trafficking to the spleen were mixtures ofCD44^(high)CD62L^(low) and CD44^(high)CD62L^(high) populations (FIG.5C). In the mice bearing parental tumors, 2C T cells present in thesecondary lymphoid organs maintained a naïve phenotype (CD62L^(high) andCD44^(low)) without significant proliferation after 14 days (FIG. 7B).Furthermore, no detectable 2C T cells, naïve or activated, presentinside the parental tumors (FIG. 7B).

2C T cell proliferation correlated with tumor rejection. Ag104L d-MutantLIGHT tumors established for 10 days in these H—Y transgenic mice werecompletely suppressed while the parental tumors grew comparably to thosein mice without 2C T cell transfer (FIG. 7D).

C3B6F1 mice were used as tumor recipients. 5×10⁶ Ag104L^(d) orAg104L^(d)-LIGHT was inoculated subcutaneously to C3B6F1 mice. 10-14days later, 3×10⁶ CFSE labeled 2C T cells were adoptively transferredinto the hosts and trafficking and proliferation of the T cells in thetumor draining lymph nodes, other non-draining lymph nodes, spleen ortumor mass were checked after 48 hours and 168 hours. It yielded similarresults as in H-Y or OT-1 TCR transgenic mice.

Naïve tumor antigen-specific T cells can be recruited to the tumor siteand they proliferated there effectively and killed the tumor cells inthe mutant LIGHT-mediated environment even when the antigens are notwell cross-presented. More significantly, these T cells were able tosuppress tumor grow in situ. Interestingly, mutant LIGHT-mediated tumorenvironment generated large amount of tumor antigen-specific T cellsthat were able to leave tumor site, re-circulate and potentially rejectother tumors in the distal sites bearing the same antigen without mutantLIGHT (TABLE 3).

Example 7 Therapeutic Vaccination with Mutant LIGHT-ExpressingAg104L^(d) Eradicates Established Parental Tumor

Mutant LIGHT-mediated tumor environment was able to recruit naïve Tcells and activate them inside the tumor and cause tumor rejection. Thepotential therapeutic efficacy of the finding was shown by injectingmutant LIGHT-expressing tumor cells into the established parental tumor.Such treatment could create a lymphoid environment to attract naïve Tcells and then activate tumor specific ones via co-stimulation in thepresence of antigen leading to the rejection of these establishedtumors. 10⁵ Ag104L^(d) was inoculated subcutaneously to C3B6F1recipients and the tumors were allowed to establish for 14 days. Then10⁶ mutant LIGHT-expressing Ag104L^(d) tumor cells were injected insidethe established parental tumors. As control, the same volume of PBS wasinjected into the tumors in the same way. The established parentaltumors treated with mutant LIGHT-expressing tumor cells continued togrow for 10-15 days before they started to regress and disappeared (FIG.8). Ag104L^(d) tumors treated with PBS grew aggressively.

Mutant LIGHT-mediated tumor environment generated many tumorantigen-specific central and effector memory T cells going back tocirculation. The generation of such a pool of lymphocytes may beimportant to eradicate metastasis after surgical removal of primarytumors. Tumor antigen-specific memory T cells with high quantity frommutant LIGHT-mediated environment may be able to reject establishedparental tumor in the distal site. To set up a clinically relevantmodel, 10⁴ Ag104L^(d) tumor cells was injected to the left flank of C3B6μl hosts and the tumors were established for 20 days. 10⁶Ag104L^(d)-mutant LIGHT tumor cells were injected 20 days later to theright flank of the mice. Alternatively, the same volume of PBS wasinjected to the Ag104L^(d)-tumor bearing mice in the control group. 100%of the mice treated with Mutant LIGHT-bearing tumor cells rejected theestablished parental tumors. Ag104L^(d) tumors grew progressively on themice in the control group 100% (Table 2).

The therapeutic efficacy of mutant LIGHT-expressing tumor cells wasdemonstrated in another model more closely simulated clinicalmetastasized tumors. 10⁶ (primary tumor) and 5×10⁴ (distal tumor)Ag104L^(d) tumor cells were inoculated into the left and right flank ofthe recipient mice, respectively. The primary tumor was surgicallyremoved 14 days after tumor inoculation and 10⁶ Mutant LIGHT-expressingAg 104L^(d) tumor cells were injected into the upper back of the mouse.Growth of the established distal tumors was observed. All the mice inthe treated group rejected the distal tumors. However, without treatmentwith mutant LIGHT-expressing tumor, the distal tumor killed all thehosts in the control group (TABLE 2).

Mutant LIGHT-mediated tumor environment is able to recruit naïve T cellsand activated and expanded tumor antigen-specific T cells and rejecttumor cells bearing the antigen in situ. Moreover, large amount of tumorantigen-specific central and effector memory-type T cells were generatedinside the environment and able to traffick to distal sites to rejecttumors bearing the same antigen (Table 3).

Delivery of mutant LIGHT by adenovirus into tumor tissues allowseffective immune response and tumor rejection. FIG. 10 illustrates thereductions of tumor volume correlated with the presence in vivo ofmutant LIGHT expression in tumor cells. FIG. 11 illustrates reduction inspontaneous metastasis in mice at days 14, 17 and until day 34 afterinoculation. There is a synergistic effect of anti-41 BB, an antibodythat stimulate T cells, on tumor reductions. FIG. 12 illustrates thatthe clonogenic assay shows no evidence of metastasis after mutant LIGHTtreatment.

Example 8 LIGHT Delivered by Adenovirus Mediates Host Resistance toTumor

To develop a clinically relevant therapeutic strategy to deliver mutantLIGHT into tumor tissue, a recombinant replication-deficient adenovirusexpressing mutant LIGHT (Ad-mutant LIGHT) was generated. To determinewhether Ad-mutant LIGHT transferred expression of LIGHT in tumor cells,three tumor cell lines (fibrosarcoma Ag104L^(d), melanoma B16-OVA, andmammary carcinoma 4T1) were infected in vitro for 24 hours. Detection ofLIGHT expression was evaluated using a soluble lymphotoxin β receptor(LTβR), one of the receptors for LIGHT. Ad-mutant LIGHT was able toconfer LIGHT expression on all three tumor cell lines (FIG. 13A). It wastested whether mutant LIGHT delivered by adenovirus could mediate therejection of an established tumor. Ag104L^(d) tumor cells were injectedsubcutaneously to the C3B6F1 mice. Ad-mutant LIGHT (5×10⁹ p.f.u.) orcontrol virus expressing LacZ (Ad-control) were injected intratumorally14 days after tumor challenge when the mass was well-established. TheAg104L^(d) tumors persisted for a few days before being completelyrejected after Ad-mutant LIGHT treatment while those treated withAd-control continued grew progressively (FIG. 13B). Tumor rejectionmediated by Ad-mutant LIGHT was CD8⁺ T cell-dependent and led to strongmemory protection against the re-challenge of Ag104L^(d) at dose as highas 10⁷ tumor cells. Ag104L^(d) tumor was able to completely regress bythe Ad-mutant LIGHT treatment. In addition, some tumors, such as a coloncancer MC38, melanoma B16-SIY and mammary cancer 4T1, which are thoughtto be more aggressive and/or display lower immunogenicity, weresignificantly inhibited in their growth (FIGS. 13C-D and FIG. 14A).These results demonstrate that Ad-mutant LIGHT injected intratumorallycan mediate partial or complete control of large established tumors.

Example 9 Ad-Mutant LIGHT Controls Spontaneous Tumor Metastases

It was determined whether Ad-mutant LIGHT treatment of the primary tumorcould induce a sufficient immune response to control disseminatedmetastases. 4T1 breast carcinoma closely mimics human breast cancer inits anatomical site, immunogenicity, growth characteristics, andmetastatic properties. It is poorly immunogenic as the surgical removalof a growing 4T1 tumor will not confer protection against re-challenge.When 10⁵ 4T1 tumor cells was injected subcutaneously into wild-type (WT)Balb/c mice, either at the mammary fat pad, or around the tail base,metastases was consistently detected in various organs and draininglymph nodes (LN) 11 days after tumor inoculation.

To determine whether the anti-tumor response generated at the primarytumor site by Ad-mutant LIGHT might be sufficient to eliminate orcontrol micro-disseminated tumor cells, the 4T1 tumor cells were firstinfected in vitro with Ad-mutant LIGHT or Ad-control. The 4T1 tumorcells infected with Ad-mutant LIGHT expressed high level of LIGHT 24hours after infection while the ones infected with Ad-control did notexpress LIGHT at a detectable level (FIG. 13A). The tumor cells werethen harvested from the culture 24 hours after Ad-mutant LIGHT infectionand 105 of mutant LIGHT-expressing or Ad-control-infected 4T1 tumorcells were inoculated subcutaneously into Balb/c mice. Primary tumorgrowing subcutaneously was monitored for 35 days before the mice weresacrificed for the evaluation of metastasis in the lung using a colonyassay. The growth of the primary tumor was hindered yet continued toprogress without being completely rejected (FIG. 14B). However, nocolonies of metastatic cells were detected in the lungs of miceinoculated with LIGHT-expressing 4T1 tumor cells while a high number ofmetastases was detected in the lungs of mice bearing control tumors(FIG. 14C). Depletion of CD8⁺ T cells abrogated this effect. The controlof metastasis may be attributed to the mutant LIGHT expressed locally inthe primary tumor since the distal metastatic tumor cells were notpossible to be infected to express mutant LIGHT in this model. Theseresults indicated that mutant LIGHT expression by the 4T1 tumor duringthe initial stage of tumor growth was sufficient to control metastasesin the presence of a growing primary tumor.

The therapeutic effects of Ad-mutant LIGHT were tested. WhetherAd-mutant LIGHT delivered directly into an established tumor wouldcontrol cancer metastasis was tested. The subcutaneous growth of 10⁵ 4T1tumor cells in Balb/c mice was established for 7 days, followed by theintra-tumor injection of 5×10⁹ p.f.u. of Ad-mutant LIGHT or Ad-control.The growth of the primary tumor was suppressed after Ad-mutant LIGHTtreatment but continued to grow. In order to mimic the clinicaltherapeutic setting, the primary tumor was surgically removed 18 daysafter the tumor inoculation. Mice were then sacrificed to evaluate themetastasis in the lung using the colonogenic assay 35 days post-primarytumor injection. Interestingly, no metastasis was detected in the lungof the mice that had been given Ad-mutant LIGHT treatment while largenumbers of metastatic cancer cells were found in the lung of the controlmice (FIG. 14D). These results demonstrated that mutant LIGHT deliveredby adenoviral gene transfer into an established primary tumor inducedsignificant tumor-specific CTL to control the occurrence of spontaneousmetastasis.

Example 10 Ad-Mutant LIGHT Mediates the Rejection of EstablishedSpontaneous Lung Metastasis

Without being bound by a particular mode or theory, there are twopossible general mechanisms by which Ad-mutant LIGHT treatment couldinhibit the number of metastatic cancer cells present in the lung. Oneis that Ad-mutant LIGHT-induced anti-tumor immunity suppresses thegrowth of the primary tumor which then prevents the exit of tumor cellsto other sites. The other is that Ad-mutant LIGHT triggers a potentanti-tumor immunity to cause rejection of already seeded distalmetastatic tumors. Given the potent anti-metastatic activity ofAd-mutant LIGHT treatment, it was examined whether Ad-mutant LIGHTtreatment would possibly be effective to treat the hosts already bearingdetectable metastasis. Since subcutaneous injection of 10⁵ 4T1 tumorcells consistently resulted in detectable metastasis in the lung 11 dayspost-tumor inoculation, Ad-mutant LIGHT treatment after the 11 day-timepoint would indicate the effectiveness of the treatment on alreadyseeded metastatic cancer cells. About 10⁵ 4T1 tumor cells wereinoculated subcutaneously to Balb/c mice, provided intra-tumoralinjection of 2×10⁹ p.f.u. of Ad-mutant LIGHT or Ad-control 14 and 17days later, then surgically removed the primary tumor 29 days afterinitial tumor inoculation. The mice were sacrificed and the metastasisin the lung was analyzed 35 days post inoculation of primary tumor.While a large number of metastatic colonies were found in the lung ofthe Ad-control-treated mice, a dramatic decrease in the number ofmetastatic cancer cells was detected in Ad-mutant LIGHT-treated mice(FIG. 15A). Local treatment of cancer with Ad-mutant LIGHT is effectiveat eradicating preexisting metastases.

In an aspect, for clinical application, surgical removal of the tumormay be necessary immediately, precluding the possibility of intratumoralinjection prior to resection. In addition, effective intratumoraldelivery of Ad-mutant LIGHT in tumors that are not readily accessiblecan be performed by introducing mutant LIGHT expressing tumor cells. Analternative strategy to deliver Ad-mutant LIGHT by vaccinating withtransduced tumor cells following surgical excision was analyzed. 4T1tumor cells were inoculated subcutaneously in Balb/c mice, followed bysurgical removal 18 days later, which is one week after the initiationof metastasis. Evidence of metastatic spread at this time point wasverified by the colonogenic assay. 4T1 cells grown in culture were theninfected with either Ad-mutant LIGHT or Ad-control for 24 hours,irradiated, and injected subcutaneously into the mammary fat pad thefollowing day. The treatment was given on days 18 and 25. Mice weresacrificed and the metastasis in the lung was examined 35 days postinoculation of primary tumor. As expected, a large number of metastasiswere present in the lung of the control mice. Surprisingly, nometastatic cancer cells were detected in mice treated with irradiatedAd-mutant LIGHT-transduced tumor cells (FIG. 15B). These results suggestthat Ad-mutant LIGHT-transduced tumor cells are part of a potenttherapeutic vaccine that is capable of mediating the rejection of seededmetastatic tumors.

Example 11 Activated Tumor Antigen-Specific T Cells Leave the MutantLIGHT-Mediated Tumor Environment and Subsequently Appear in the LymphoidTissues

Delivery of mutant LIGHT by adenovirus intratumorally induced stronganti-tumor immunity and caused rejection of spontaneous metastasis.Ad-mutant LIGHT stimulates tumor-specific CD8⁺ T cells from within thetumor and generate effector/memory T cells that subsequently circulatesystemically and reject the disseminated tumor cells. However, it isdifficult to confirm that the activated tumor-specific T cells detectedin draining LN come from tumor or are generated in draining LN becausecross-presentation of tumor antigens can occur in both compartments. Toclearly distinguish whether the tumor antigen-specific T cells areactivated first in the tumor or in lymphoid tissues, a system in whichreactive T cells recognize antigen only through direct presentation ontumor cells was used. In B6/OT-1/Rag-1^(−/−) hosts (H-2^(b)) (OT-1mice), adoptively transferred 2C TCR transgenic T cells recognizing Ag104L^(d) tumors, a fibrosarcoma transfected to express H-2L^(d), cannotbe activated by indirect presentation, but can only be activated bydirect presentation of the aberrant MHC class I molecule. These hostmice lack endogenous T cells reactive to the Ag 104L^(d) tumor, and 2C Tcells are the only T cells mediating the anti-tumor responses. Inaddition, 2C T cells cannot undergo homeostatic expansion on transferinto these mice in the presence of CD8⁺ OT-1 T cells. Thus, the primingby the Ag104L^(d) tumors is dependent on the direct presentation to 2C Tcells in the tumor in this model. In addition, to focus on studying thelocal effects of mutant LIGHT and avoid the potential for systemicspreading of Ad-mutant LIGHT that could reach lymphoid organs,Ag104L^(d) or mutant LIGHT-expressing Ag104L^(d) tumor lines were used.

The subcutaneous inoculation of 10⁶ Ag104L^(d) or Ag104L^(d) -mutantLIGHT cells in OT-1 mice was followed after 10-14 days by the infusionof 3×10⁶ CFSE-labeled 2C T cells. The presence of activated 2C T cellswas evaluated 14-20 days after adoptive transfer in the draining lymphnodes (DLNs), non-DLNs and spleen, and in the tumor itself. A largenumber of activated 2C T cells were observed displaying high surfaceexpression of CD44 and production of IFN-γ were present inside themutant LIGHT-expressing Ag104L^(d) tumors (FIG. 16A). In contrast,activated 2C T cells were barely detectable in the parental Ag 104L^(d)tumors. At this time point, a higher percentage of activated 2C T cellsin the lymphoid tissues including DLN, non-DLN and spleen was found(FIG. 16A). These activated 2C T cells all expressed high level of CD44and IFN-γ (FIG. 16A). Some activated antigen-specific T cells arecapable of migrating out of the tumor and into systemic circulationfollowing local expression of mutant LIGHT inside the tumor.

Example 12 Activated Tumor Antigen-Specific T Cells Generated from thePrimary Tumor Move to the Distal Tumor

It was determined whether the exiting tumor antigen-specific T cellscould then patrol peripheral tissues to infiltrate a distal secondarytumor mass which does not express mutant LIGHT. To avoid the potentialfor systemic spreading of Ad-mutant LIGHT that could reach the distaltumor, Ag104L^(d) or mutant LIGHT-expressing Ag104L^(d) tumor lines wereused to address whether local presence of mutant LIGHT in primary tumorcan evoke an anti-tumor immunity on the distal tumors. The same modelsystem described herein, in which 2C T cells were adoptively transferredto Ag104L^(d) tumor-bearing OT-1 mice was used, but this time inoculatedeach of the OT-1 mice with two tumors. The primary tumor was either 10⁶Ag104L^(d) or Ag104L^(d)-mutant LIGHT, while the secondary tumor was 10⁵Ag104L^(d). 10-14 days post tumor challenge, CFSE-labeled 2C T cellswere transferred. Proliferation of the 2C T cells was evaluated at days3, 5 and 10 after adoptive transfer inside the tumors. Three days aftertransfer, CFSE^(hi) non-proliferating 2C cells were present in themutant LIGHT-expressing Ag104L^(d) primary tumor. Subsequentproliferation of these 2C T cells was observed 5 days after transfer, asindicated by the in situ dilution of CFSE. By day 10, a larger number ofproliferated 2C T cells was found in Ag104L^(d)-mutant LIGHT tumors(FIG. 16B). In the secondary Ag104L^(d) tumor, the presence of dilutedCFSE labeled 2C T cells was detected at a higher frequency in micebearing Ag104L^(d)-mutant LIGHT tumor compared to those bearingAg104L^(d) (FIGS. 16 B and C). Only a small population of tumorinfiltrating 2C T cells was detected in both the primary and thesecondary tumor of the mice bearing two Ag104L^(d) tumors (FIG. 16C).These data support the notion that some activated antigen-specific Tcells are able to migrate out of the primary tumor after mutant LIGHTtreatment and traffic to the secondary tumor.

Example 13 Ad-Mutant LIGHT at the Primary Tumor Generates more CTLs

Antigen-specific T cells activated in the mutant LIGHT-mediatedenvironment were capable of migrating to a distal tumor that did notexpress mutant LIGHT. To test whether Ad-mutant LIGHT can generate moreCTL against tumor from primary tumor, which then circulate systemicallyfor the rejection of distal tumor, adoptive transfer experiments wereperformed to investigate whether the T cells from lymphoid organs oftreated mice are capable of mediating the rejection of establishedtumors. 4T1 model cannot be used for these experiments since thesecondary lymphoid tissues are often contaminated with metastatic 4T1tumor cells 2 weeks after tumor challenge. About 10⁵ Ag104L^(d) tumorcells were inoculated to the C3B6F1 mice, then treated with 5×10⁹ p.f.u.of Ad-mutant LIGHT or Ad-control 14 days post tumor inoculation. At 21days the spleen and lymph nodes were collected from the treated mice andthe T cells were purified and adoptively transferred 10⁷ of these Tcells to C3B6F1 mice bearing an Ag104L^(d) tumor that has beenestablished for 7 days. The mice that received T cells from Ad-mutantLIGHT-treated mice all rejected their tumors while the ones thatreceived T cells from Ad-control-treated mice died of tumor burdens(FIG. 16D). This result suggested that activated antigen-specific Tcells present in circulation after Ad-mutant Mutant LIGHT treatment, butnot control virus, are sufficient to reject established distal tumors.These results demonstrate that local treatment of tumor with Ad-mutantLIGHT can generate more CTL entering the draining LN, which then attackestablished distal tumors.

Example 14 Ad-Mutant LIGHT Treatment at Local Site Enhances TCell-Mediated Responses at Local and Distal Sites

To assess whether Ad-mutant LIGHT treatment directly alters tumorenvironment at the primary tumor and the distal site, C3B6F1 mice wereinoculated with two subcutaneous Ag104L^(d) tumors 6 days apart, tomimic development of a new subcutaneous metastasis. The intra-tumoralAd-mutant LIGHT treatment of the primary tumor was given 5 days afterthe secondary tumor inoculation. Both the primary and secondary tumorswere rejected in the mice treated with Ad-mutant LIGHT while the micetreated with Ad-control developed tumor progression (FIG. 17A). Becausethe effect of Ad-mutant LIGHT is CD8-mediated, the percentage of CD8⁺ Tcells among the Ly5.2⁺ leukocytes, and IFN-γ-producing effectors amongall the CD8⁺ T cells in the DLNs, spleen, primary and secondary tumorswere examined. The number of CD8⁺ T cells and IFN-γ-producing effectorCD8⁺ T cells increased dramatically in both the primary and thesecondary tumors after Ad-mutant LIGHT treatment (FIGS. 17B and C). Thedevelopment of anti-tumor immunity leading to tumor regression isgenerally associated with a change of the cytokine environment. Toexamine the cytokine millieu in the lymphoid organs, and inside thetumor itself, the spleen and tumor tissues 7 days after Ad-mutant LIGHTor Ad-control treatment were harvested, the tissues were ground and thesupernatant was collected for cytokine measurement. None of thecytokines that was tested, TNF-α, IFN-γ, IL-2, IL-4, IL-5, IL-6,significantly changed in the spleen of mice treated with Ad-mutant LIGHTcomparing to the ones treated with Ad-control. However, TNF-α and IFN-γincreased considerably in both of the primary and the secondary tumorswith Ad-mutant LIGHT treatment (FIG. 17D). Thus, tumor rejection wasaccompanied by an increase of CD8⁺ T cells, enhancement of the IFN-γproduction by the effector CD8⁺ T cells, and augmentation ofinflammatory cytokines TNF-α and IFN-γ inside both the primary andsecondary tumors. These results demonstrated that Ad-mutant LIGHTtreatment on the primary tumor can generate large numbers of effectorcells from the tumor and these cells can efficiently survey peripheraltissues and respond to distal tumors, leading to the regression of asecondary tumor burden.

Example 15 Gene Modification of Light Enhances its Expression in “293Cells”

This example demonstrates mutant LIGHT expression in 293 cells (FIG.18). 293 cells, a human kidney cell line, are commonly and easily usedfor transient expression of gene at relative high level of gene. 293cells were seeded in 6 well plate and transfected with 2 μg DNA ofpAdCMVmLIGHT (wild type murine LIGHT), pAdCMVmmLIGHT (mutant murineLIGHT) or pAdCMVcommLIGHT (codon optimized mutant murine LIGHT byGNENART, Berlin, Germany). Codon modification is to optimize gene codonto allow higher expression of protein without changing proteinsequences. Transfection was performed using Lipofectmin 2000 reagent. 48hours after transfection, cells were detached and incubated withrecombinant mLTbR-huFc protein (10 μg/ml) followed by staining with PEconjugated Donkey anti-human IgG antisera. Cells were washed andanalyzed by flowcytometry (BD FACSArray Bioanalyzer). Transfection werecarried out in triplicates and only one representative result is shown.Upper panel shows the histogram of flowcytometry. Cells were alsoexamined visually by fluorescent microscopy. Representative results areshown in lower panel. (see FIG. 18). High expression of LIGHT isrequired to have stronger response. However, protease digestion of LIGHToften reduces its stability on cell surface. This example showed thatour gene modification and mutation greatly enhances LIGHT expression oncell surface.

Example 16 Coupling or Conjugating Mutant LIGHT Expression to a TumorTargeting Agent

In an aspect, to enable delivery of mutant LIGHT expressing deliverysystem or an equivalent delivery system, mutant LIGHT can be coupled orconjugated to a tumor targeting agent such as a tumor specific antibody.For example, a tumor specific antibody can be conjugated to LIGHT can beused to selectively deliver fusion protein to tumor site. In addition, atumor specific antibody can be designed to be expressed in the surfaceof a viral delivery system or a liposome vehicle can be coated with atumor specific antibody. The delivery vehicle expressing the mutantLIGHT and harboring the tumor targeting agent will first target thespecific tumor cell and then transform the tumor cell to express mutantLIGHT on the surface of tumor cells. This targeted mutant LIGHTexpression on the surface of the tumor cells will induce chemokines onstromal cells surrounding tumor to attract and initiate priming ofT-cells. Such treatments are suitable to all tumors, especially solidtumor. 4T1, MC38, B16, and mastocytoma were treated with ad-LIGHT andshowed reduction of primary and/or secondary tumor. Therefore,LIGHT-antibody can be used to target various tumors, especially theirmetastasis. For example, through systemic injection, anti-her2/neuantibody with LIGHT can carry LIGHT to metastatic tumor that expressesher2/neu and then can generate local immune response to clear tumor.Therefore, the fusion protein can be delivered through any systemic andlocal route and the fusion protein will be more localized to tumor dueto the specificity of antibody or another agent to tumor antigens.

TABLE 1 Mutant LIGHT augments host's resistance to Ag104L^(d) tumorchallenges Incidence of Tumor cells injected^(a) tumor growth^(b)(Percentage) Ag104L^(d) 5 × 10⁶ 10/10 (100) 1 × 10⁶ 11/11 (100) 5 × 10⁵10/10 (100) 1 × 10⁵ 5/5 (100) 5/10⁴ 4/4 (100) 1 × 10⁴ 4/4 (100)Ag104L^(d) - 5 × 10⁵ clone H10  0/10  (0) mutant LIGHT 1 × 10⁶ clone H10 0/11  (0) 5/10⁶ clone H10  0/10  (0) 5/10⁶ bulk  0/10  (0) ^(a)Numberof tumor cells as indicated were injected subcutaneously to C3B6F1 mice.^(b)The results were pooled from 1 to 3 independent experiments.

TABLE 2 Incidence of Ag104Ld tumors in C3B6F1 mice Incidence of Tumorcells injected Treatment tumor growth^(a) (Percentage) 10⁶ Ag104L^(d) notreatment 16/16 (100) 10⁶ Ag104L^(d) CD8-depletion^(b) 6/6 (100) 10⁶Ag104L^(d)-LIGHT^(m) No treatment 0/6  (0) 10⁶ Ag104L^(d)-LIGHT^(m)CD8-depletion^(b) 6/6 (100) 10⁶ Ag104L^(d)-LIGHT^(m) LTβR-Ig^(c) 6/6(100) 10⁷ Ag104L^(d) 10⁶ Ag 104L^(d)- 0/5  (0) LIGHT 40 days ago 10⁷Ag104L^(d) 10⁶ Ag 104L^(d)- 0/5  (0) LIGHT 60 days ago ^(a)The resultswere pooled from 1 to 4 independent experiments. ^(b)CD8+ cells weredepleted by anti-CD8 antibody. Depletion was confirmed by checkingperipheral blood samples. ^(c)100 μg of LTβR-Ig was injected on the dayof tumor challenge to each recipient.

TABLE 3 Treatment with Ag104L^(d)-mutant LIGHT eradicates establishedtumors at distal sites. Ag104L^(d) tumor cells Days of tumor Incidenceof injected establishment^(a) Treatment tumor growth (Percentage) 10⁴ 20days No treatment 4/4 (100) 10⁴ 20 days 105 Ag104L^(d)-mutant 0/4  (0)LIGHT^(b) 5 × 10⁴ 20 days No treatment 4/4 (100) 5 × 10⁴ 20 days 106Ag104L^(d)-mutant 2/4  (50) LIGHT^(b) 10⁶ 14 days Surgical removal ofprimary 4/4 (100) (primary) + 5 × 10⁴(distal) tumor 10⁶ 14 days Surgicalremoval of primary 0/4  (0) (primary) + 5 × 10⁴(distal) tumor & 10⁶Ag104L^(d)- mutant LIGHT^(b) 5 × 10⁶ 20 days Surgical removal of primary4/4 (100) (Primary) + 10⁶(distal) tumor 5 × 10⁶ 20 days Surgical removalof primary 2/4  (50) (primary) + 10⁶(distal) tumor & 10⁶ Ag104L^(d)-mutant LIGHT^(b) ^(a)Days of growth of subcutaneously injectedAg104L^(d) in the hosts before treatment started ^(b)10⁶ Ag104L^(d)-mutant LIGHT tumor cells were injected subcutaneously at other site thanwhere Ag104L grew.

The introduction of mutant LIGHT, a ligand for stroma expressedlymphotoxin receptor and T cell expressed HVEM, inside the tumorenvironment elicited high level of chemokines and adhesion molecules,accompanied by massive infiltration of naïve T lymphocytes. In anaspect, mutant LIGHT, has a proteolytic site EKLI (SEQ ID NO: 4) frompositions 79-82 deleted from the amino acid sequence of normal murineLIGHT (FIG. 3A) (Tamada et al., 2000). Mutant LIGHT enhances rejectionof an established, highly progressive parental tumor at local and distalsites. Mutant LIGHT-expressing tumor cells are the basis for aclinically relevant therapeutic and prophylactic vaccines to eradicatewell-established parental tumors and prevent new tumors forming throughmetastasis.

Materials and Methods

Mice, Cell Lines, and Reagents. Female C3HXC57BL/6 F1 (C3B6F1) mice, 4-8weeks old were purchased from the National Cancer Institute, FrederickCancer Research Facility, (Frederick, Md.). C57BL/6-RAG-1-deficient(RAG-1^(−/−)) mice were purchased from the Jackson Laboratory (BarHarbor, Me.). H-Y TCR transgenic mice (H-Y mice) on theRAG-2-deficient/B6 background were purchased from Taconic Farms(Germantown, N.Y.). 2C TCR transgenic mice on RAG-1-deficient backgroundbred into B6 for 10 generations (2C mice) were provided by J. Chen(Massachusetts Institute of Technology, Boston, Mass.). OT-1 TCRtransgenic mice (OT-1 mice) were provided by A. Ma (The University ofChicago). RAG-1^(−/−), H—Y, 2C, OT-1 mice were bred and maintained inthe specific pathogen-free facility at the University of Chicago. Animalcare and use were in accord with institutional guidelines.

The AG 104A fibrosarcoma grew out spontaneously in an aging C3H mouseand was adapted to culture as described (Ward 1989 JEM). The AG104Aexpressing murine H-2L^(d) (AG104-L^(d)), the transfectant of AG104Acells, has been described previously (Wick M, 1997, JEM). These tumorcell lines were maintained in DMEM (Mediatech) supplemented with 10% FCS(Sigma-Aldrich), 100 U/ml penicillin, and 100 μg/ml streptomycin(BioWhittaker). The hybridoma cell lines producing anti-L^(d) (clone30-5-7) and anti-2C TCR (1B2) antibodies were obtained from D. Sachs(National Institutes of Health, Bethesda, Md.) and T. Gajweski (TheUniversity of Chicago), respectively.

Monoclonal antibodies produced by hybridomas were purified from theculture supernatant with protein G column by standard procedure. The 1B2antibody was conjugated to FITC or biotin by the Monoclonal AntibodyFacility of The University of Chicago. PE-coupled anti-CD8 antibody,Cy-chrome (CyC)-coupled streptavidin, CyC-coupled anti-CD44 antibody,PE-coupled anti-CD62L antibody and PE-coupled Th1.2 antibody werepurchased from BD Biosciences. FITC-conjugated-goat-anti-mouse IgG waspurchased from Caltag. PE-coupled streptavidin was purchased fromImmunotech. PE-coupled donkey anti-human IgG was purchased from JacksonImmunological Research Lab (West grove, Pa.). Biotinylated goat anti-SLCantibody was purchased from R&D systems Inc. (Minneapolis, Minn.). APconjugated rabbit anti-goat Ig antibody was purchased from VectorLaboratories Inc. (Burlingame, Calif.). Purified goat anti-SLC antibodywas purchased from PeproTech (Rock hill, NJ). Collagenase (type 4) waspurchased from Sigma-Aldrich. CFSE was purchased from Molecular Probes.HVEM-Ig and LTβR-Ig fusion proteins used in this study have beendescribed previously.

Generation of B7.1 or mutant LIGHT Expression Vectors and Clones Togenerate pMFG-S-mutant LIGHT, pcDNA3.1-mutant LIGHT was digested withNcoI and BamHI and ligated to a NcoI and BamHI-digested the pMFG-S-TPAplasmid (Dr. Mulligan R C, Massachusetts Institute of Technology,Boston, Mass.). φNxEco packaging cells producing the viruses containingmutant LIGHT was generated by transient transfection with MFG-S-mutantLIGHT by calcium precipitation method. The expression of mutant LIGHT byinfected AG104L^(d) tumor cells (AG104L^(d)-mutant LIGHT bulk) wasassayed by staining the cells with a rabbit anti-serum recognizingmutant LIGHT. Subsequently, the infected mutant LIGHT-expressingAG104L^(d) tumor cells were cloned by limiting dilution method.AG104L^(d)-mutant LIGHT clone H10 was one of these clones used in theexperiments.

Tumor Growth In Vivo. Tumor cells were injected subcutaneously into thelower back, that is, 0.5-1 cm above the tail base of the mice. Tumorgrowth was measured every 3 to 4 days with a caliper. Size in cubiccentimeters was calculated by the formula V=πabc/6, where a, b, and care three orthogonal diameters.

Histology. Tumor tissues for histology examination were collected attime indicated and fixed in 10% neutral buffered formalin, processed toparaffin embedment, and stained with hematoxylin and eosin. Forimmunohistochemical staining of SLC, tumor tissues were harvested,embedded in OCT compound (Miles-Yeda, Rehovot, Israel) and frozen at−70° C. Frozen sections (5-10 μm thick) were fixed in cold 2% formalinin PBS and permeablized with 0.1% saponin/PBS. The sections werepreblocked with 5% goat serum in 0.1% saponin/PBS for half an hour atroom temperature in a humidified chamber. Staining for SLC was done byfirst incubating with biotinylated goat anti-SLC antibody (R&D systemsInc. Minneapolis, Minn.) at a 1/25 dilution in blocking buffer. Alkalinephosphatase conjugated rabbit anti-goat Ig antibody (Vector LaboratoriesInc. Burlingame, Calif.) was added 2 h later. For immunofluorescencestaining, sections were blocked with 2% normal mouse serum, rabbitserum, and goat serum in PBS for half an hour at room temperature in ahumidified chamber. Blocking solution was replaced with 50 μl of primaryAbs, PE-conjugated anti-Th1.2 (BD PharMingen), or PE-conjugated anti-CD8(BD PharMingen), diluted 1/100 in blocking solution, and sections wereincubated for 1 h at room temperature in a humid chamber. Specimens weremounted in Mowiol 4-88 (BD Biosciences, La Jolla, Calif.) containing 10%1,4-diazobicyclo [2.2.2]octane. Samples were analyzed within 48 h usinga Zeiss Axioplan microscope (Zeiss, Oberkochen, Germany) and aPhotometrics PXL CCD camera (Photometrics, Tucson, Ariz.). No-neighbordeconvolution was performed using Openlab v2.0.6 (Improvision,Lexington, Mass.).

ELISA for CCL21. Tumor homogenates were prepared and assayed for CCL21.Comparable amount of tumor tissues from tumor-bearing mice werecollected and weighed, homogenized in PBS that contained proteaseinhibitors, and the supernatants were collected by centrifugation.Polystyrene 96-well microtiter plates (Immulon 4, Dynatech Laboratories,Chantilly, Va.) were coated with goat anti-mouse CCL21 at 2 μg/ml in PBSand were then blocked with 0.1% bovine serum albumin (BSA) in PBS for 30min at room temperature. After washing, serial dilutions of standards ofknown concentrations (Recombinant CCL21, 50 ng/ml, R&D) and samples wereadded and incubated for 2 h at room temperature. After 3 washes,biotinylated rabbit anti-SLC Ab was added to the wells. After 2 hincubation and washing, 50 μl of a 1/1000 diluted alkalinephosphatase-conjugated avidin (Dako) was added for 1 h and thendeveloped. Color development was measured at 405 nm on an automatedplate reader (Spectra-Max 340, Molecular Devices, Sunnyvale, Calif.) andThe amount of CCL21 was determined by ELISA from the standard curve, andnormalized according to tissue weight. Data are mean±s.d.

Real-time quantitative RT-PCR assay. Real-time PCR was performed. TotalRNA from tumors was isolated with Absolute RNA miniprep Kit (Stratagene,La Jolla, CA) and digested with DNaseI (Life Technologies, Grand Island,NY) to remove chromosomal DNA. The remaining DNaseI was inactivated at75° C. for 20 min and integrity of RNA was assessed by visualization ofethidium bromide-stained gels. 5 μg of total RNA was reverse transcribedinto cDNA with the First Strand cDNA Synthesis kit (Amersham Pharmacia,Piscataway, NJ). The real-time quantitative PCR analysis was done on theABI Prism 7700-sequence detection system (PE Applied Biosystems). Theprimer sequences for CCL21 were 5′-AGACTCAGGAGCCCAAAGCA-3′ (SEQ ID NO:5) (forward primer) 5′-GTTGAAGCAGGGCA AGGGT-3′ (SEQ ID NO: 6) (reverseprimer), and the probe for CCL21 was 5′-CCACCTCATGCTGGCCTCCGTC-3′ (SEQID NO: 7). The primers for MAdCAM-1 were 5′-GACACCAGCTTGGGCAGTGT-3′ (SEQID NO: 8) (forward primer) and 5′-CAGCATGCCCCGTACAGAG-3′ (SEQ ID NO: 9)(reverse primer), and the probe for MAdCAM-1 was5′-CAGACCCTCCCAGGCAGCAGTATCC-3′ (SEQ ID NO: 10). The primers for GAPDHwere 5′-TTCACCACCATGGAGAAGGC-3′ (SEQ ID NO: 11) (forward primer) and5′-GGCATGGACT GTGGTCATGA-3′ (SEQ ID NO: 12) (reverse primer), and theprobe for GAPDH was 5′-TGCATCCTG CACCACCAACTGCTTAG-3′ (SEQ ID NO: 13).The CCL21 and MAdCAM-1 probes were labeled with 6-carboxy-fluorescein(FAM). The GAPDH probe was labeled withtetrachloro-6-carboxy-fluorescein (TET). Each cDNA sample was amplifiedin duplex for CCL21 and GAPDH or MAdCAM-1 and GAPDH with the TaqManUniversal PCR master mixture containing AmpliTaq Gold DNA Polymeraseaccording to the manufacturer's instructions (PE Applied Biosystems).PCR conditions were 2 min at 50° C., 10 min at 95° C., 15 s at 95° C.and 1 min at 60° C. for 40 cycles. The concentration of target gene wasdetermined using the comparative C_(T) (threshold cycle number atcross-point between amplification plot and threshold) method andnormalized to the internal GAPDH control.

Tumor tissue chemokine microarray For these experiments, GEArray Qseries Mouse Chemokines and Receptors Gene Array membrane (SuperArray,Bethesda, Md.) were used. Total RNA from tumors was isolated withAbsolute RNA miniprep Kit (Stratagene, La Jolla, Calif.) and digestedwith DNaseI (Life Technologies, Grand Island, N.Y.) to removechromosomal DNA. The remaining DNaseI was inactivated at 75° C. for 20min. Integrity of RNA was assessed by visualization of ethidiumbromide-stained gels. The microarrays were employed according to themanufacturer's instructions. In brief, using reagents provided, cDNA wasprepared from total RNA by reverse transcription with MMLV reversetranscriptase, radiolabeled using [−32P] dCTP (3,000 Ci/mM), thenhybridized under precisely specified conditions to a positively chargednylon membrane containing the arrayed DNA. After washing, the arrayswere visualized by phosphorimager. Loading was adjusted based onintensity of hybridization signals to the housekeeping genes, PUC18,actin and GAPDH, then gene expression was quantitated after the digitalimage recorded by phosphorimager was converted to digital data by usingImageQuant software. The raw data was analyzed using the GEArrayAnalyzersoftware according to manufacturer's instructions.

T-cell co-stimulation assay. T cells were purified by a negativeselection method in the magnetic field as instructed by the manufacture(Miltenyi Biotec, Auburn, Calif.). The purity of isolated T cells wasgreater than 95%, as assessed by flow cytometry using monoclonalantibody against CD3. Plates coated with 0.2 g/ml monoclonal antibodyagainst CD3 were further coated at 37° C. for 4 h with MutantLIGHT-flag. After being washed, purified T cells (1×10⁶ cells/ml) werecultured in the wells. Monoclonal antibody against CD28 (1 μg/ml) wasused in soluble form. In all assays, the proliferation of T cells wasassessed by the addition of 1 Ci/well ³H-thymidine during the last 15 hof the 3-day culture. 3H-thymidine incorporation was measured in aTopCount microplate scintillation counter (Packard instrument, Meriden,Conn.).

Analysis of Cells by FACS. In order to confirm that mutant LIGHT bindsto LTβR and HVEM, AG104L^(d) tumor cells transfected with mutant LIGHT(AG104Ld-mutant LIGHT) were incubated with LTβR-Ig or HVEM-Ig (0.02mg/mL), washed, and stained with PE-coupled donkey anti-human IgG orFITC-coupled goat anti-mouse IgG, respectively. For analysis of L^(d)expression, tumor cells were incubated with the anti-L^(d) antibody,washed, and incubated with FITC-coupled anti-mouse IgG antibody. Fordetection of proliferation of CFSE-labeled 2C T cells, isolated lymphnode (LN) cells, splenocytes, and tumor-infiltrating T cells (TIL) werestained with biotinylated 1B2 antibody, washed, and stained withCyC-coupled streptavidin and PE-coupled anti-CD8. For analysis ofCFSE-labeled 2C T cells and CD44 expression, isolated LN cells,splenocytes or TIL were stained with biotinylated 1B2 antibody, washed,and stained with a mixture of PE-coupled streptavidin and CyC-coupledanti-CD44. For analysis of CFSE-labeled 2C T cells and CD62L expression,isolated LN cells, splenocytes or TIL were stained with biotinylated 1B2antibody, washed, and stained with CyC-coupled streptavidin andPE-coupled anti-CD62L. Samples were analyzed on a FACScan and data wasanalyzed with CELLQuest or FlowJo softwares.

Adoptive Transfer of 2C T Cells. LN cells and splenocytes were isolatedfrom 2C mice and CD8⁺ T cells were negatively selected with a CD8⁺ Tcell enrichment kit (Miltenyi Biotec, Auburn, Calif.). Whenanalyzed, >90% of the enriched CD8⁺ cells expressed the 2C receptor.Approximately 3×10⁶ 2C T cells were transferred into H-Y or OT-1 micefor assays of tumor growth. The same number of 2C T cells wastransferred to each mouse in each experiment. To transfer CFSE-labeled Tcells, T cells at a concentration of 2×10⁷/ml were labeled with 10 μMCFSE in PBS at 37° C. for 30 min. The cells were quenched with equalvolume of FCS for 1 min and washed three times, and 3×10⁶ CFSE-labeled Tcells were injected intravenously into the retro-orbital plexus in a0.2-ml volume to the tumor-bearing mice. Cells were isolated from theinguinal lymph nodes (DLNs), the other lymph nodes (nondraining lymphnodes [NDLN]), spleen or tumors at the time indicated.

Cell depletions and in vivo blockage of Mutant LIGHT activity withLTβR-Ig Mice were depleted of lymphocyte subsets by standard procedures(current protocol for immunology) using monoclonal antibody (mAb) GK1.5(Dialynas DM JI 1983) for CD4+ cells, and mAb 2,34 for CD8+ cells(Sarmiento M 1980 JI). Examination of splenocytes and lymph node cellsby FACS revealed that the depleted subset represented <0.5% of the totallymphocytes, with normal levels of other subsets. To block Mutant LIGHTin mice, the LTβR-Ig (100 μg/injection) were given the same day and aweek after tumor challenge, intra-peritoneally.

Cell Isolation from tumor tissue. The mice were first bled to decreasethe blood contamination of tumor tissue. The tumor tissues werecollected, washed in the PBS, cut into pieces, and resuspended in DMEMsupplemented with 2% FCS and 1.25 mg/ml collagenase D (collagenase Dsolution) for 40 min in a 37° C. shaking incubator. The single cellsuspension was collected after 40 min, and the cell clumps were digestedfor another 40 min in the collagenase D solution until all tumor tissuehad resolved into a single cell suspension.

Delivery of LIGHT and Mutant LIGHT expressing cells. Delivery of anucleic acid encoding mMutant LIGHT into a patient may be either direct,in which case the patient is directly exposed to the nucleic acid ornucleic acid-carrying vectors, or indirect, in which case, tumor cellsobtained from a biopsy are first transformed with the nucleic acids invitro, irradiated and then transplanted into the patient. Theseapproaches are routinely practiced in gene therapies for suppressingtumors or treating other illness.

Delivery of nucleic acids. The nucleic acid sequences encoding mutantLIGHT are directly administered in vivo or can be introduced into tumorcells in vitro, where they are expressed to produce mutant LIGHTprotein. This can be accomplished by any of numerous methods known inthe art, e.g., by constructing them as part of a suitable nucleic acidexpression vector and administering it so that they becomeintracellular, e.g., by infection using defective or attenuatedretroviral or other viral vectors, or by direct injection of naked DNA,or by use of microparticle bombardment, or coating with lipids orcell-surface receptors or transfecting agents, encapsulation inliposomes, microparticles, or microcapsules, or by administering them infusion with a peptide that enters the nucleus, by administering bycoupling with a ligand subject to receptor-mediated endocytosis (whichcan be used to target cell types specifically expressing the receptors),etc. Alternatively, the nucleic acid can be introduced intracellularlyand incorporated within host cell DNA for expression, by homologousrecombination. Mode of delivery of mutant LIGHT into tumor cells orother cells is not limited to a particular delivery method.

Biodegradable microspheres have also been used in gene delivery systemsthat encapsulate the nucleic acid. Microspheres such as matrices, films,gels and hydrogels which include hyaluronic acid (HA) derivatized with adihydrazide and crosslinked to a nucleic acid forming slow releasemicrospheres have been used to deliver nucleic acids. Controlled releasegene delivery system utilizing poly(lactide-co-glycolide) (PLGA),hydroxypropylmethyl cellulose phthalate, cellulose acetate phthalate,and copolymer microspheres to encapsulate the gene vector are alsoknown.

Therapeutic compositions used herein can be formulated intopharmaceutical compositions comprising a carrier suitable for thedesired delivery method. Suitable carriers include materials that whencombined with the therapeutic composition retain the anti-tumor functionof the therapeutic composition. Examples include, but are not limited toa number of standard pharmaceutical carriers such as sterile phosphatebuffered saline solutions, bacteriostatic water, and the like.Therapeutic formulations can be solubilized and administered via anyroute suitable to deliver the therapeutic composition to the tumor site.Potentially effective routes of administration include, but are notlimited to, intravenous, parenteral, intraperitoneal, intramuscular,intratumor, intradermal, intraorgan, orthotopic, and the like. Aformulation for intravenous injection comprises the therapeuticcomposition in a solution of preserved bacteriostatic water, sterileunpreserved water, and/or diluted in polyvinylchloride or polyethylenebags containing sterile sodium chloride for injection. Therapeuticprotein preparations can be lyophilized and stored as sterile powders,preferably under vacuum, and then reconstituted in bacteriostatic water(containing for example, benzyl alcohol preservative) or in sterilewater prior to injection. Dosages and administration protocols for thetreatment of cancers using the methods disclosed herein may vary withthe method and the target cancer, and generally depend on a number offactors appreciated and understood in the art.

Delivery using viral vectors. Viral vectors that contain nucleic acidsequences encoding mutant LIGHT are used for delivering nucleic acids.For example, a retroviral vector can be used. These retroviral vectorscontain the components necessary for the correct packaging of the viralgenome and integration into the host cell DNA. The nucleic acidsequences encoding the mutant LIGHT protein are cloned into one or morevectors, which facilitates delivery of the gene. Adenoviruses aresuitable vehicles for delivering genes to various tissue targetsincluding respiratory epithelia and other targets for adenovirus-baseddelivery systems are liver, the central nervous system, endothelialcells, and muscle. Adenoviral vectors are also suitable for targetingnucleic acid delivery to tumor cells. Adenoviruses have the advantage ofbeing capable of infecting non-dividing cells. Adeno-associated virus(AAV) has also been proposed for use in gene delivery. Lentiviruses arealso suitable vehicles for use in gene delivery.

Transfecting cells in tissue culture followed by delivery to patients.Another approach to gene therapy involves transferring a gene to cellsin tissue culture by such methods as electroporation, lipofection,calcium phosphate mediated transfection, or viral infection. Usually,the method of transfer includes the transfer of a selectable marker tothe cells. The cells are then placed under selection to isolate thosecells that have taken up and are expressing the transferred gene. Thosecells are then delivered to a patient. In this method, the nucleic acidis introduced into a cell prior to administration in vivo of theresulting recombinant cell. Such introduction can be carried out by anymethod known in the art, including but not limited to transfection,electroporation, microinjection, infection with a viral or bacteriophagevector containing the nucleic acid sequences, cell fusion,chromosome-mediated gene transfer, microcell-mediated gene transfer,spheroplast fusion, etc. The technique should provide for the stabletransfer of the nucleic acid to the cell, so that the nucleic acid isexpressible by the cell and preferably heritable and expressible by itscell progeny.

The resulting recombinant cells may be irradiated and can be deliveredto a patient by various methods known in the art. Recombinant cells(e.g., hematopoietic stem or progenitor cells) are preferablyadministered intravenously. The amount of cells envisioned for usedepends on the desired effect, patient state, etc., and can bedetermined by one skilled in the art. Cells into which a nucleic acidcan be introduced for purposes of gene therapy encompass any desired,available cell type, and include but are not limited to epithelialcells, endothelial cells, keratinocytes, fibroblasts, muscle cells,hepatocytes, blood cells such as T lymphocytes, B lymphocytes,monocytes, macrophages, neutrophils, eosinophils, megakaryocytes,granulocytes; various stem or progenitor cells, in particularhematopoietic stem or progenitor cells, e.g., as obtained from bonemarrow, umbilical cord blood, peripheral blood, fetal liver, etc.

Vaccines. As used herein, the term “vaccine” refers to a composition(e.g., a Mutant LIGHT antigen and an adjuvant) that elicits atumor-specific immune response. These vaccines include prophylactic(preventing new tumors) and therapeutic (eradicating parental tumors). Avaccine vector such as a DNA vaccine encoding mutant LIGHT can be usedto elicit immune response against tumors. The response is elicited fromthe subject's own immune system by administering the vaccine compositionat a site (e.g., a site distant from the tumor). The immune response mayresult in the eradication of tumor cells in the body (e.g., both primaryand metastatic tumor cells). Methods for generating tumor vaccines arewell known in the art (See e.g., U.S. Pat. Nos. 5,994,523 and 6,207,147each of which is herein incorporated by reference).

The vaccines may comprise one or more tumor antigens in a pharmaceuticalcomposition. In some cases, the tumor antigen is inactivated prior toadministration. In other embodiments, the vaccine further comprises oneor more additional therapeutic agents (e.g., cytokines or cytokineexpressing cells).

In certain cases, cells selected from a patient, such as fibroblasts,obtained, for example, from a routine skin biopsy, are geneticallymodified to express one or of the desired protein. Alternatively,patient cells that may normally serve as antigen presenting cells in theimmune system such as macrophages, monocytes, and lymphocytes may alsobe genetically modified to express one or more of the desired antigens.The antigen expressing cells are then mixed with the patient's tumorcells (e.g., a tumor antigen), for example in the form of irradiatedtumor cells, or alternatively in the form of purified natural orrecombinant tumor antigen, and employed in immunizations, for examplesubcutaneously, to induce systemic anti-tumor immunity. The vaccines maybe administered using any suitable method, including but not limited to,those described above.

Clonogenic assay. Clonogenic Assay for the Lung. Materials neededinclude DMEM 5% FCS (+p/s, HEPES); Collagenase type IV (Sigma); 60 μM6-thioguanine; 50 ml conical tubes; 6 well tissue culture plates; 37° C.shaking incubator/tissue culture incubator; dissecting equipment:scissors, curved scissors, and forceps; 70 μm nylon cell strainers; ACKlysis; methanol; 0.03% (w/v) methylene blue solution. Preparation ofcollagenase medium has the following steps: to approx 25 ml medium pernumber of lung, add collagenase to make the medium 1.5 mg/mlconcentration. To prepare a lung sample: (1) Remove lung from mouse andtransfer it to a 6 well plate; 2) Add approx 200 μl of medium on thelung; 3) with curved scissors, mince the lung into small pieces; 4) usethe curved portion of the closed scissors, transfer minced lung into a50 ml conical tube 5 ml of collagenase medium; 5) add 5 ml of medium tothe wells and pipette out and transfer the remaining lung pieces to theconical tube; 6) place in shaking incubator for 20 minutes at 37° C. at175 r.p.m.; 7) pour the supernatant through a cell strainer into a clean50 ml conical tube-any lung pieces on the cell strainer should return tothe conical tube for a second digestion; 8) spin down at 1500 r.p.m. for5 min in centrifuge; 9) discard supernatant after spinning down; 10)resuspend pellet in 1 ml of fresh collagenase free medium; 11) performACK lysis for 5 minutes; 12) count cells; 13) plate 3×10⁵, 3×10⁴, 3×10³cells into 12 well plate; 14) add 60 μM 6-thioguanine into each well;and 15) place plate in 37° C. tissue culture incubator, 5% CO₂ for 5-10days.

Harvesting clonogenic metastatic colonies includes the following steps:(not necessary but easier to count colonies)—discard culture media fromtissue culture plate; fix cells by adding 5 ml of methanol to each plateand swirl; and incubate at room temperature for 5 min (colonies shouldturn white); discard methanol and rinse each plate gently with 5 mldistilled water; (the cells should not come in contact with water untilafter the cells have been fixed); add 5 ml 0.03% (w/v) methylene bluesolution to each plate; swirl to cover entire plate and incubate at roomtemperature for 5 min; discard dye and rinse plate gently with 5 mldistilled water; allow plate to air dry before counting blue colonies(one colony represents one clonogenic metastatic cells).

Mice and Cell Line. Female C3HXC57BL/6 F1 (C3B6F1), C57BL/6 and Balb/cmice, 4-8 weeks old were purchased from the National Cancer Institute,Frederick Cancer Research Facility (Frederick, Md.). 2C TCR transgenicmice on RAG-1^(−/−)/B6 background (2C mice) were provided by J. Chen(Massachusetts Institute of Technology, Boston, Mass.). OT-1 TCRtransgenic mice on RAG-1^(−/−)/B6 background (OT-1 mice) were providedby A. Ma (The University of California at San Francisco). 2C and OT-1mice were bred and maintained in the specific pathogen-free facility atthe University of Chicago. Animal care and experiments were done inaccordance with institutional and National Institutes of Health (NIH)guidelines and were approved by an animal use committee at theUniversity of Chicago. The Ag104A fibrosarcoma expressing murineH-2L^(d) (AG104-L^(d)) as described herein (see also Wick et al., 1997).B16-SIY melanoma cell line was generated as described in Blank et al.,(2004). B16-OVA and 4T1 tumor, which is a 6-thioguanine-resistant cellline derived from a spontaneous mammary carcinoma, were both provided byZhaoyang You, University of Pittsburgh. MC38 colon cancer cell line wasprovided by Y Liu (Ohio State University). Ag 104L^(d) and 4T1 tumorcells lines were grown in DMEM supplemented with 10% fetal calf serum(FCS). B16-OVA, B16-SIY and MC38 tumor cells were grown in RPMIsupplemented with 10% fetal calf serum (FCS).

The generation of adenovirus-expressing mutant LIGHT. The mutant murineLIGHT (mmLIGHT) was generated as described herein. To constructrecombinant mmLIGHT-Adenovirus, a BamH1/NotI fragment containing murinemutant LIGHT cDNA cut from pCDN3.1-mmLIGHT was cloned into the BamH/NotIsites of the first parental plasmid, pLEP-ubp (left end plasmid, Tetr)after human ubiquitin promoter (ubp). Subsequently, the pLEP-mmLIGHT wasligated to a second plasmid, pREP (right end plasmid, Ampr) at a uniqueintron-encoded Cla I site. The ligation product was packaged with λphage packaging extracts. The pLEP/pREP hybrid cosmids were selectedgrown on Amp/Tet LB agar plate. Bgl II digestion was used to furtheridentify recombinant cosmid containing insert mmLIGHT. The Adv-mmLIGHTDNA fragment was liberated from its recombinant cosmid by I-Ceu Idigestion, and the mixture of I-CeuI digestion without furtherpurification was transfected into 293 cells for recombinant adenovirusproduction (Adv-mmLIGHT).

Tumor injection, treatments and evaluation of metastases by colonogenicassay. For Ag104L^(d) tumors, C3B6F1 mice were inoculated subcutaneouslyinto the area around the tail base with the dose described in theresults. For B16-SIY and MC38 tumors, B6 mice were inoculatedsubcutaneously into the area around the tail base with 10⁶ or 10⁵ tumorcells, respectively. For 4T1 tumors, Balb/c mice were inoculatedsubcutaneously into the area around the tail base or into the mammaryfat pad with 105 tumor cells. The tumor nodules were inoculated withAd-mutant LIGHT or Ad-control virus intratumorally in 50 μl PBScontaining indicated amount of virus particles and p.f.u. For surgicalexcision of primary 4T1 tumors, mice were anesthetized before surgery,and tumors were resected with sterilized instruments. Wounds were closedwith metallic clips. All mice survived surgery. Mice in which primarytumors recurred at the site of the surgical excision were eliminatedfrom the experiments. For evaluation of metastases, lungs was collectedand chopped before being dissociated in DMEM supplemented with 5% of FCScontaining 1.5 mg/ml collagenase type 4 (Sigma) for 30 minutes in 37° C.shaking incubator at 178 rpm speed. Organs were then plated at variousdilutions in the DMEM supplemented with 10% FCS and 60 μM 6-thioguanine.Individual colonies representing micrometastasis were counted after 5-10days.

In vitro infection and vaccination with irradiated tumor cells. 1×10⁶cells were plated in 100 mm cell culture dish for 24 hours then infectedwith Ad-Control or Ad-mutant LIGHT at 4×10⁸ p.f.u./ml for 24 hours.Cells were harvested and checked for mutant LIGHT expression by FACSstaining with LTβR-Ig at 0.02 mg/mL followed by PE-coupled donkeyanti-human IgG (Jackson, West grove, Pa.). For vaccination, tumor cellsharvested after infection and confirmed for mutant LIGHT expression wereirradiated at 1500 rads prior to subcutaneous injection into the mammaryfat pad. All infections were performed in an approved biohazard hood.

Analysis of Cells by FACS. In order to detect mutant LIGHT expression onthe tumor cells, Ag104L^(d), B16-OVA, B16-SIY, MC38 and 4T1 tumor cellsinfected with Ad-mutant LIGHT were incubated with LTβR-Ig at 0.02 mg/mLfollowed by PE-coupled donkey anti-human IgG (Jackson, West grove, Pa.).For detection of proliferation and expression of CD44 and IFN-γ byCFSE-labeled 2C T cells, isolated lymph node (LN) cells, splenocytes,and tumor-infiltrating T cells (TIL) were stained as described herein(see also Yu et al., 2003, 2005). Samples were examined on a FACScan anddata was analyzed with FlowJo softwares (Becton Dickinson, FranklinLakes, N.J.).

Measurement of cytokines in the spleen and tumor. We prepared tumor andspleen homogenates as described (Yu et al., 2003). Briefly, comparableamounts of tumor or spleen tissues were collected, weighed andhomogenized in PBS containing protease inhibitors, and the supernatantswere collected by centrifugation. The amount of cytokines in thesupernatants was quantified using the cytometric bead array kit (CBA)(BD Biosciences) on a FACS Caliber cytometer equipped with CellQuestProand CBA software (Becton Dickinson) according to manufacture'sinstruction.

Adoptive Transfer of 2C T Cells. LN cells and splenocytes were isolatedfrom 2C mice and CD8⁺ T cells were negatively selected with a CD8⁺ Tcell enrichment kit (Miltenyi Biotec, Auburn, Calif.). Whenanalyzed, >90% of the enriched CD8⁺ cells expressed the 2C receptor.Approximately 3×10⁶ 2C T cells were transferred into OT-1 mice forassays of tumor growth. The same number of 2C T cells was transferred toeach mouse in each experiment. To transfer CFSE-labeled T cells, T cellswere labeled with CFSE as described herein (see also Yu et al., 2003).3×10⁶ CFSE-labeled T cells were injected intravenously into theretro-orbital plexus in a 0.2-ml volume to the tumor-bearing mice. Cellswere isolated from the inguinal lymph nodes (DLNs), the other lymphnodes (nondraining lymph nodes (NDLN)), spleen (SPL) or tumors at thetime indicated.

Cell Isolation from tumor tissue. The mice were first bled to decreasethe blood contamination of tumor tissue. The tumor tissues werecollected, washed in the PBS, cut into pieces, and resuspended in DMEMsupplemented with 5% FCS and 1.5 mg/ml collagenase D (collagenase Dsolution) for 40 min in a 37° C. shaking incubator. The single cellsuspension was collected after 40 min, and the cell clumps were digestedfor another 40 min in the collagenase D solution until all tumor tissuehad resolved into a single cell suspension.

Statistical analysis for difference in tumor growth. Because the tumorgrowth was observed repeatedly over time on the same mouse, the randomeffect models for longitudinal data were used to analyze such data. Foreach experiment, the tumor growth was assumed to depend on treatment andto follow a linear growth rate over time. The model gave an overallestimate of the intercept and slope of the linear growth for each group.Both the intercept and slope were allowed to vary among individualmouse. The slope, i.e., the growth rate was compared was different amongdifferent treatment groups. Because the actual tumor growth may notfollow a linear growth trend over the entire follow up period. Theincrease of tumor growth was slow at the early stage and became rapid atthe later stage in some experiments. A quadratic term was added to thefollow-up time in the above random effect models.

Wild type human LIGHT DNA sequence (SEQ ID NO: 14) (sequence encoding aprotease site EQLI (SEQ ID NO: 17) is shown in bold):

    ATGGAGGAGAGTGTCGTACGGCCCTCAGTGTTTGTGGTGGATGGACAGACCGACATCCCATTCACGAGGCTGGGACGAAGCCACCGGAGACAGTCGTGCAGTGTGGCCCGGGTGGGTCTGGGTCTCTTGCTGTTGCTGATGGGGGCTGGGCTGGCCGTCCAAGGCTGGTTCCTCCTGCAGCTGCACTGGCGTCTAGGAGAGATGGTCACCCGCCTGCCTGACGGACCTGCAGGCTCCTGG GAGCAG CTGATACAAGAGCGAAGGTCTCACGAGGTCAACCCAGCAGCGCATCTCACAGGGGCCAACTCCAGCTTGACCGGCAGCGGGGGGCCGCTGTTATGGGAGACTCAGCTGGGCCTGGCCTTCCTGAGGGGCCTCAGCTACCACGATGGGGCCCTTGTGGTCACCAAAGCTGGCTACTACTACATCTACTCCAAGGTGCAGCTGGGCGGTGTGGGCTGCCCGCTGGGCCTGGCCAGCACCATCACCCACGGCCTCTACAAGCGCACACCCCGCTACCCCGAGGAGCTGGAGCTGTTGGTCAGCCAGCAGTCACCCTGCGGACGGGCCACCAGCAGCTCCCGGGTCTGGTGGGACAGCAGCTTCCTGGGTGGTGTGGTACACCTGGAGGCTGGGGAGAAGGTGGTCGTCCGTGTGCTGGATGAACGCCTGGTTCGACTGCGTGATGGTACCCGGTCTTACTTCGGGGCTTTCATGGTGTGA-3′

Native human LIGHT amino acid sequence (SEQ ID NO: 15) (proteasedigestion site is bold underlined):

    MEESVVRPSVFVVDGQTDIPFTRLGRSHRRQSCSVARVGLGLLLLLMGAGLAVQGWFLLQLHWRLGEMVTRLPDGPAGSW EQLI QERRSHEVNPAAHLTGANSSLTGSGGPLLWETQLGLAFLRGLSYHDGALVVTKAGYYYIYSKVQLGGVGCPLGLASTITHGLYKRTPRYPEELELLVSQQSPCGRATSSSRVWWDSSFLGGVVHLEAGEKVVVRVLDERLVRLRDGTRSYFGAFMV

One aspect of a mutant human LIGHT amino acid sequence (SEQ ID NO: 16)(EQLI (SEQ ID NO: 17) is absent, indicated by dots):

MEESVVRPSVFVVDGQTDIPFTRLGRSHRRQSCSVARVGLGLLLLLMGAGLAVQGWFLLQLHWRLGEMVTRLPDGPAGSW . . . QERRSHEVNPAAHLTGANSSLTGSGGPLLWETQLGLAFLRGLSYHDGALVVTKAGYYYIYSKVQLGGVGCPLGLASTITHGLYKRTPRYPEELELLVSQQSPCGRATSSSRVWWDSSFLGGVVHLEAGEKVVVRVLDERLVRLRDGTRSYFGAFMV

Codon optimized nucleotide sequence for mouse mutant LIGHT, starting ATGis highlighted in bold: (SEQ ID NO: 18)

  1 GGGCGAATTGGGTACCGGATCCGCGACCATGGAGAGCGTGGTGCAGCCCAGCGTGTTCGT−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+  61GGTGGACGGCCAGACCGACATCCCCTTCAGGAGGCTGGAGCAGAACCACAGGCGGAGGAG−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 121ATGTGGCACCGTGCAGGTGTCCCTGGCCCTGGTGCTGCTGCTGGGCGCTGGCCTGGCCAC−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 181CCAGGGCTGGTTTCTGCTGAGGCTGCACCAGAGGCTGGGCGACATCGTGGCCCACCTGCC−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 241CGATGGCGGCAAGGGCAGCTGGCAGGACCAGAGGAGCCACCAGGCCAACCCTGCCGCCCA−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 301CCTGACAGGCGCCAACGCCAGCCTGATCGGCATCGGCGGACCCCTGCTGTGGGAGACCAG−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 361GCTGGGCCTGGCTTTCCTGAGGGGCCTGACCTACCACGACGGCGCCCTGGTGACCATGGA−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 421GCCCGGCTACTACTACGTGTACAGCAAGGTGCAGCTGTCCGGAGTGGGCTGCCCTCAGGG−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 481CCTGGCCAACGGCCTGCCCATCACCCACGGCCTGTACAAGAGGACCAGCAGATACCCCAA−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 541GGAGCTGGAGCTGCTGGTCTCCAGGCGGAGCCCCTGTGGCAGGGCCAACAGCAGCCGAGT−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 601GTGGTGGGACAGCAGCTTCCTGGGCGGCGTGGTGCACCTGGAGGCCGGCGAGGAGGTGGT−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 661GGTGAGGGTGCCCGGCAACAGGCTGGTGAGGCCCAGGGACGGCACCAGGAGCTACTTCGG−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+ 721CGCCTTCATGGTGTGATGAGCGGCCGCGAGCTCCAGCTTTTGTTCCC−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−−−+−−−−−−−

Codon optimized nucleotide sequence for human mutant LIGHT, starting ATGis highlighted in bold. (SEQ ID NO: 19)

GAATTCGAGCTCGGTACCCGAGACGGTACCGGATCCGCCACCATGGAGGAGAGCGTTGTGAGGCCCAGCGTGTTCGTGGTGGACGGCCAGACCGACATCCCCTTCACCCGGCTGGGCCGGAGCCACCGGAGGCAGAGCTGCTCCGTGGCCAGAGTGGGGCTGGGCCTGCTGCTCCTGCTGATGGGAGCCGGCCTGGCCGTGCAGGGCTGGTTCCTGCTGCAGCTGCACTGGCGGCTGGGCGAGATGGTGACCCGGCTGCCCGATGGCCCTGCCGGCAGCTGGCAGGAGCGGCGGAGCCACGAGGTGAACCCTGCCGCCCACCTGACCGGCGCCAACAGCAGCCTGACCGGCAGCGGCGGACCCCTGCTGTGGGAGACCCAGCTGGGCCTGGCCTTCCTGAGGGGCCTGAGCTACCACGACGGCGCCCTGGTGGTGACCAAGGCCGGCTACTACTACATCTACAGCAAGGTGCAGCTGGGCGGAGTGGGCTGCCCTCTGGGGCTGGCCAGCACCATCACCCACGGCCTGTACAAGCGGACCCCCAGATACCCCGAGGAGCTGGAGCTGCTGGTGTCCCAGCAGAGCCCCTGTGGCAGGGCCACCTCCAGCAGCCGGGTGTGGTGGGACAGCAGCTTCCTGGGCGGCGTGGTGCACCTGGAGGCCGGCGAGAAAGTGGTTGTGAGGGTGCTGGACGAGCGGCTTGTGAGGCTGAGGGACGGCACCCGGAGCTACTTCGGCGCCTTCATGGTGTGATGAGCGGCCGCGAGCTCGTCTCGGGGATCCTCTAGAGTCGACCTGCAGGCATGCAAGCTTG

Generation of mutant LIGHT Expression Vectors and Clones pcDNA3.1-LIGHTwas used as template to generate two dsDNA fragments A and B by PCR. Forgeneration of fragment A (˜500 b.p.), sense primer5′-CATGGATCCAAGACCATGGAGAGTGTGGTACA-3′ (SEQ ID NO: 20) (the bold textindicated BamHI site) and antisense primer5′-AGATCGTTGATCTTGCCAGGAGCCTTTGCC-3′ (SEQ ID NO: 21) were used. Togenerate fragment B (˜200 b.p.), sense primer5′-GGCAAAGGCTCCTGGCAAGATCAACGATCT-3′ (SEQ ID NO: 22) and antisenseprimer 5′-ACCTCTAGATCAGACCATGAAAGCTCCGA-3′ (SEQ ID NO: 23) (theunderlined text indicated XbaI site) were used. The antisense primer forfragment A is complimentary with sense primer for fragment B, whichcovers sequences for amino acid (a.a.) 73-87 among which a.a. 79-82 weredeleted. Fragments A and B were mixed, denatured at 94° C. and cooleddown to room temperature to anneal the two DNA fragments. The annealedDNA product was used as template for a PCR reaction and the product wascloned into pcDNA3.1 using BamHI and XbaI. The deletion of a.a. 79-82was verified by sequencing. To generate pMFG-mutant LIGHT,pcDNA3.1-mutant LIGHT was digested with NcoI and BamHI and ligated to aNcoI and BamHI-digested the pMFG-S-TPA plasmid (Mulligan RC,Massachusetts Institute of Technology, Boston, MA).

PUBLICATIONS CITED

The publications cited are incorporated by reference to the extent theyrelate to the present invention.

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1. A method of reducing tumor burden, the method comprising: (a)introducing a mutant human LIGHT (homologous to lymphotoxin, exhibitsinducible expression, and competes with HSV glycoprotein D for herpesvirus entry mediator, a receptor expressed by T lymphocytes) protein ora fragment comprising an extracellular domain of native LIGIIT into atumor site, wherein the mutant LIGHT protein or the LIGHT fragment isresistant to protease digestion and is stably present on the tumor cellsurface, wherein the mutant LIGHT has an amino acid change in aproteolytic site comprising an amino acid sequence EQLI (SEQ ID NO: 17)from positions 81-84 of native LIGHT protein, or does not have theproteolytic site; and (b) reducing tumor burden by stimulatingactivation of tumor-specific T-cells against the tumor by the stablepresence of protease resistant mutant LIGHT.
 2. The method of claim 1,wherein the mutant LIGHT protein is introduced directly into the tumorsite.
 3. The method of claim 1, wherein the mutant LIGHT protein isintroduced adjacent to the tumor site.
 4. The method of claim 1, whereinthe tumor burden is reduced by stimulation of cytotoxic T-lymphocytes.5. The method of claim 1, wherein the tumor burden is reduced bystimulation of production of chemokines, adhesion molecules, andcostimulatory molecules for priming naïve T-cells.
 6. The method ofclaim 1 wherein the tumor burden measured is metastastic disease.
 7. Themethod of claim 1, wherein the mutant LIGHT protein or a fragmentcomprising the extracellular domain of native LIGHT is expressed on thetumor cell surface following introduction of a nucleic acid molecule. 8.A method of reducing tumor burden, the method comprising: (a)introducing a mutant human LIGHT (homologous to lymphotoxin, exhibitsinducible expression, and competes with HSV glycoprotein D for herpesvirus entry mediator, a receptor expressed by T lymphocytes) fragmentcomprising an extracellular domain of native LIGHT wherein theextracellular domain of native LIGHT comprises SEQ ID NO: 1 in which oneor more of the amino acids EQLI (SEQ ID NO: 17) from positions 81-84 ofnative LIGHT protein, is either deleted or mutated, into a tumor site,wherein the mutant LIGHT fragment is resistant to protease digestion andis stably present on the tumor cell surface; and (b) reducing tumorburden by stimulating activation of tumor-specific T-cells against thetumor by the stable presence of protease resistant mutant LIGHT.